How do privacy experts and lay persons differ? We investigate this question using data about the use of privacy-enhancing technologies and strategies from 128 surveys and 17 follow-up interviews with two populations: privacy experts (i.e., privacy researchers and professionals) and privacy laypersons. Findings reveal that both experts and laypersons use common privacy strategies, but experts employ a broader range of strategies, favor open source technologies, and possess a more technical understanding of internet privacy risks and technologies such as onion routing and tracking algorithms. We characterize these differences in terms of sociological habitus, where experts and laypersons differ not only in technical skill but also in broader conceptualizations and practices. From this characterization, we make recommendations for technology design practices, as well as legal and pedagogical implications, that can help decenter the experiences of privacy experts and accommodate privacy laypersons' preferences and habits.

People Search Websites, a category of data brokers, collect, catalog, monetize and often publicly display individuals' personally identifiable information (PII). We present a study of user privacy rights in 20 such websites assessing the usability of data access and data removal mechanisms. We combine insights from these two processes to determine connections between sites, such as shared access mechanisms or removal effects. We find that data access requests are mostly unsuccessful. Instead, sites cite a variety of legal exceptions or misinterpret the nature of the requests. By purchasing reports, we find that only one set of connected sites provided access to the same report they sell to customers. We leverage a multiple step removal process to investigate removal effects between suspected connected sites. In general, data removal is more streamlined than data access, but not very transparent; questions about the scope of removal and reappearance of information remain. Confirming and expanding the connections observed in prior phases, we find that four main groups are behind 14 of the sites studied, indicating the need to further catalog these connections to simplify removal.

Activism efforts have played a central role in advancing the rights of disabled people in the United States. Social media offers new opportunities for people with disabilities to engage in activism while bypassing the accessibility issues involved in traditional activism. At the same time, disabled people face various forms of social and technical exclusion that may also complicate their use of social media for disability activism. To understand how disabled activists advocate for social change online, we interviewed 20 disabled content creators about their goals, strategies, and challenges around posting activism content on social media. We find that visibility is essential for successful online activism, but that the pursuit of visibility requires disabled content creators to navigate additional challenges including social stigma, algorithmic suppression, accessibility issues, and a heightened risk of harassment. We identify three main types of disability-related harassment faced by disabled activists, along with six ways in which they respond to such harassment. We examine the sociotechnical nature of the strategies disabled activists use to gain visibility, and identify key trade-offs involved in mitigating harassment while engaging in activism on social media.

The emergent, dynamic nature of privacy concerns in a shifting sociotechnical landscape creates a constant need for privacy-related resources and education. One response to this need is community-based privacy groups. We studied privacy groups that host meetings in diverse urban communities and interviewed the meeting organizers to see how they grapple with potentially varied and changeable privacy concerns. Our analysis identified three features of how privacy groups are organized to serve diverse constituencies: situating (finding the right venue for meetings), structuring (finding the right format/content for the meeting), and providing support (offering varied dimensions of assistance). We use these findings to inform a discussion of “privacy pluralism” as a perennial challenge for the HCI privacy research community, and we use the practices of privacy groups as an anchor for reflection on research practices.

This qualitative study examines the privacy challenges perceived by librarians who afford access to physical and electronic spaces and are in a unique position of safeguarding the privacy of their patrons. As internet “service providers,” librarians represent a bridge between the physical and internet world, and thus offer a unique sight line to the convergence of privacy, identity, and social disadvantage. Drawing on interviews with 16 librarians, we describe how they often interpret or define their own rules when it comes to privacy to protect patrons who face challenges that stem from structures of inequality outside their walls. We adopt the term “intersectional thinking” to describe how librarians reported thinking about privacy solutions, which is focused on identity and threats of structural discrimination (the rules, norms, and other determinants of discrimination embedded in institutions and other societal structures that present barriers to certain groups or individuals), and we examine the role that low/no-tech strategies play in ameliorating these threats. We then discuss how librarians act as "privacy intermediaries" for patrons, the potential analogue for this role for developers of systems, the power of low/no-tech strategies, and implications for design and research of privacy-enhancing technologies (PETs).

We examine how a diverse global readership assigns trust to Wikipedia articles, and the strategies they use to assess Wikipedia’s credibility. Through surveys and interviews, we develop and refine a Wikipedia trust taxonomy that describes the mechanisms by which readers assess the credibility of Wikipedia articles. Our findings suggest that readers draw on direct experience, established online content credibility indicators, and their own mental models of Wikipedia’s editorial process in their credibility assessments. Our findings can help the development of general online information assessment frameworks and the design of open collaboration systems to support credibility evaluation and trust calibration.

People who are marginalized experience disproportionate harms when their privacy is violated. Meeting their needs is vital for developing equitable and privacy-protective technologies. In response, research at the intersection of privacy and marginalization has acquired newfound urgency in the HCI and social computing community. In this literature review, we set out to understand how researchers have investigated this area of study. What topics have been examined, and how? What are the key findings and recommendations? And, crucially, where do we go from here? Based on a review of papers on privacy and marginalization published between 2010-2020 across HCI, Communication, and Privacy-focused venues, we make three main contributions: (1) we identify key themes in existing work and introduce the Privacy Responses and Costs framework to describe the tensions around protecting privacy in marginalized contexts, (2) we identify understudied research topics (e.g., race) and other avenues for future work, and (3) we characterize trends in research practices, including the under-reporting of important methodological choices, and provide suggestions to establish shared best practices for this growing research area.

People Search Websites aggregate and publicize users’ Personal Identifiable Information (PII), previously sourced from data brokers. This paper presents a qualitative study of the perceptions and experiences of 18 participants who sought information removal by hiring a removal service or requesting removal from the sites. The users we interviewed were highly motivated and had sophisticated risk perceptions. We found that they encountered obstacles during the removal process, resulting in a high cost of removal, whether they requested it themselves or hired a service. Participants perceived that the successful monetization of users PII motivates data aggregators to make the removal more difficult. Overall, self management of privacy by attempting to keep information off the internet is difficult and its’ success is hard to evaluate. We provide recommendations to users, third parties, removal services and researchers aiming to improve the removal process.

While the Internet has dramatically increased the exposure that research can receive, it has also facilitated harassment against scholars. To understand the impact that these attacks can have on the work of researchers, we perform a series of systematic interviews with researchers including academics, journalists, and activists, who have experienced targeted, Internet-facilitated harassment. We provide a framework for understanding the types of harassers that target researchers, the harassment that ensues, and the personal and professional impact on individuals and academic freedom. We then study preventative and remedial strategies available, and the institutions that prevent some of these strategies from being more effective. Finally, we discuss the ethical structures that could facilitate more equitable access to participating in research without serious personal suffering.

Social media companies wield power over their users through design, policy, and through their participation in public discourse. We set out to understand how companies leverage public relations to influence expectations of privacy and privacy-related norms. To interrogate the discourse productions of companies in relation to privacy, we examine the blogs associated with three major social media platforms: Facebook, Instagram (both owned by Facebook Inc.), and Snapchat. We analyze privacy-related posts using critical discourse analysis to demonstrate how these powerful entities construct narratives about users and their privacy expectations. We find that each of these platforms often make use of discourse about "vulnerable" identities to invoke relations of power, while at the same time, advancing interpretations and values that favor data capitalism. Finally, we discuss how these public narratives might influence the construction of users' own interpretations of appropriate privacy norms and conceptions of self. We contend that expectations of privacy and social norms are not simply artifacts of users' own needs and desires, but co-constructions that reflect the influence of social media companies themselves.

Privacy and surveillance are central features of public discourse around use of computing systems. As the systems we design and study are increasingly used and regulated as potential instruments of surveillance, HCI researchers-even those whose focus is not privacy-find themselves needing to understand privacy in their work. Concepts like contextual integrity and boundary regulation have become touchstones for thinking about privacy in HCI. In this paper, we draw on HCI and privacy literature to understand the limitations of commonly used theories and examine their assumptions, politics, strengths, and weaknesses. We use a case study from the HCI literature to illustrate conceptual gaps in existing frameworks where privacy requirements can fall through. Finally, we advocate vulnerability as a core concept for privacy theorizing and examine how feminist, queer-Marxist, and intersectional thinking may augment our existing repertoire of privacy theories to create a more inclusive scholarship and design practice.

User-generated content sites routinely block contributions from users of privacy-enhancing proxies like Tor because of a perception that proxies are a source of vandalism, spam, and abuse. Although these blocks might be effective, collateral damage in the form of unrealized valuable contributions from anonymity seekers is invisible. One of the largest and most important user-generated content sites, Wikipedia, has attempted to block contributions from Tor users since as early as 2005. We demonstrate that these blocks have been imperfect and that thousands of attempts to edit on Wikipedia through Tor have been successful. We draw upon several data sources and analytical techniques to measure and describe the history of Tor editing on Wikipedia over time and to compare contributions from Tor users to those from other groups of Wikipedia users. Our analysis suggests that although Tor users who slip through Wikipedia's ban contribute content that is more likely to be reverted and to revert others, their contributions are otherwise similar in quality to those from other unregistered participants and to the initial contributions of registered users.

Anonymity can enable both healthy online interactions like support-seeking and toxic behaviors like hate speech. How do online service providers balance these threats and opportunities? This two-part qualitative study examines the challenges perceived by open collaboration service providers in allowing anonymous contributions to their projects. We interviewed eleven people familiar with organizational decisions related to privacy and security at five open collaboration projects and followed up with an analysis of public discussions about anonymous contribution to Wikipedia. We contrast our findings with prior work on threats perceived by project volunteers and explore misalignment between policies aiming to serve contributors and the privacy practices of contributors themselves.

Web development is a learning context with the potential to support rich computational thinking. Large-scale analysis of compilation and runtime errors have been used in introductory programming courses and similar approaches can be used to understand learning in web development environments. We investigated activity logs of a novel web coding game to uncover learning trajectories and what people struggle with when learning flexible box (flexbox), a collection of new CSS layout features. We designed a game called Flexbox Froggy, in which learners solve challenges by writing a few lines of CSS code, moving from simple levels that require knowledge of one flexbox property, to complex levels combining multiple properties. We investigate learning curves based on the changes in syntactic and semantic errors learners make as they complete the game. Our findings show that people performed better encountering a single new property than combined with properties they had already practiced. Clusters of learners at different levels did not demonstrate expected error rates based on learning curve theory. Also unexpectedly, advanced groups that mastered syntax had higher semantic error rates than the beginner group, especially when attempting new properties or complex use cases. We conclude with implications for designing and developing introductory web programming games and other instructional materials.

By choice or by necessity, some contributors to commons-based peer production sites use privacy-protecting services to remain anonymous. As anonymity seekers, users of the Tor network have been cast both as ill-intentioned vandals and as vulnerable populations concerned with their privacy. In this study, we use a dataset drawn from a corpus of Tor edits to Wikipedia to uncover the character of Tor users' contributions. We build in-depth narrative descriptions of Tor users' actions and conduct a thematic analysis that places their editing activity into seven broad groups. We find that although their use of a privacy-protecting service marks them as unusual within Wikipedia, the character of many Tor users' contributions is in line with the expectations and norms of Wikipedia. However, our themes point to several important places where lack of trust promotes disorder, and to contributions where risks to contributors, service providers, and communities are unaligned.

What does reliability mean for building a grounded theory? What about when writing an auto-ethnography? When is it appropriate to use measures like inter-rater reliability (IRR)? Reliability is a familiar concept in traditional scientific practice, but how, and even whether to establish reliability in qualitative research is an oft-debated question. For researchers in highly interdisciplinary fields like computer-supported cooperative work (CSCW) and human-computer interaction (HCI), the question is particularly complex as collaborators bring diverse epistemologies and training to their research. In this article, we use two approaches to understand reliability in qualitative research. We first investigate and describe local norms in the CSCW and HCI literature, then we combine examples from these findings with guidelines from methods literature to help researchers answer questions like: "should I calculate IRR?" Drawing on a meta-analysis of a representative sample of CSCW and HCI papers from 2016-2018, we find that authors use a variety of approaches to communicate reliability; notably, IRR is rare, occurring in around 1/9 of qualitative papers. We reflect on current practices and propose guidelines for reporting on reliability in qualitative research using IRR as a central example of a form of agreement. The guidelines are designed to generate discussion and orient new CSCW and HCI scholars and reviewers to reliability in qualitative research.

Pregnancy loss is a common experience that is often not disclosed in spite of potential disclosure benefits such as social support. To understand how and why people disclose pregnancy loss online, we interviewed 27 women in the U.S. who are social media users and had recently experienced pregnancy loss. We developed a decision-making framework explaining pregnancy loss disclosures on identified social network sites (SNS) such as Facebook. We introduce network-level reciprocal disclosure, a theory of how disclosure reciprocity, usually applied to understand dyadic exchanges, can operate at the level of a social network to inform decision-making about stigmatized disclosures in identified SNSs. We find that 1) anonymous disclosures on other sites help facilitate disclosure on identified sites (e.g., Facebook), and 2) awareness campaigns enable sharing about pregnancy loss for many who would not disclose otherwise. Finally, we discuss conceptual and design implications. CAUTION: This paper includes quotes about pregnancy loss.

In this multi-method study, we examine citation activity on English-language Wikipedia to understand how information claims are supported in a non-scientific open collaboration context. We draw on three data sources-edit logs, interview data, and document analysis-to present an integrated interpretation of citation activity and found pervasive themes related to controversy and conflict. Based on this analysis, we present and discuss information fortification as a concept that explains online citation activity that arises from both naturally occurring and manufactured forms of controversy. This analysis challenges a workshop position paper from Group 2005 by Forte and Bruckman, which draws on Latour's sociology of science and citation to explain citation in Wikipedia with a focus on credibility seeking. We discuss how information fortification differs from theories of citation that have arisen from bibliometrics scholarship and are based on scientific citation practices.

Indirect disclosure strategies include hinting about an experience or a facet of one's identity or relaying information explicitly but through another person. These strategies lend themselves to sharing stigmatized or sensitive experiences such as a pregnancy loss, mental illness, or abuse. Drawing on interviews with women in the U.S. who use social media and experienced pregnancy loss, we investigated factors guiding indirect disclosure decisions on social media. Our findings include 1) a typology of indirect disclosure strategies based on content explicitness, original content creator, and content sharer, and 2) an examination of indirect disclosure decision factors related to the self, audience, platform affordances, and temporality. We identify how people intentionally adapt social media and indirect disclosures to meet psychological (e.g., keeping a personal record) and social (e.g., feeling out the audience) needs associated with loss. We discuss implications for design and research, including features that support disclosures through proxy, and relevance for algorithmic detection and intervention. CAUTION: This paper includes quotes about pregnancy loss.

When people disclose information on social media that is sensitive or potentially stigmatized (e.g., mental illness, pregnancy loss), how do others decide to respond? We use interviews and vignettes to provide a response decision-making framework (RDM) that explains factors informing whether and how individuals respond to sensitive disclosures from their social media connections. The RDM framework includes factors related to the self, poster, and disclosure context (i.e., relational, temporal, social). Our findings include how people's decisions are complicated by balancing their own needs (e.g., privacy, wellbeing) as well as the posters’ (e.g., support) when seeing what they consider sensitive posts on social media. We identify empirically grounded insights and information that social media designs could surface to support both potential disclosers and responders. We argue that social media sites should provide privacy controls for both disclosers and responders, and facilitate the visibility of network-level support.

Seeking and providing support is challenging. When people disclose sensitive information, audience responses can substantially impact the discloser's wellbeing. We use mixed methods to understandresponses toonline sexual abuse-related disclosures on Reddit. We characterize disclosure responses, then investigate relationships between post content, comment content, and anonymity. We illustrate what types of support sought and provided in posts and comments co-occur. We find that posts seeking support receive more comments, and comments from “throwaway” (i.e., anonymous) accounts are more likely on posts also from throwaway accounts. Anonymous commenting enables commenters to share intimate content such as reciprocal disclosures and supportive messages, and commenter anonymity is not associated with aggressive or unsupportive comments. We argue that anonymity is an essential factor in designing social technologies that facilitate support seekingandprovision in socially stigmatized contexts, and provide implications for social media site design. CAUTION: This article includes content about sexual abuse.

People can benefit from disclosing negative emotions or stigmatized facets of their identities, and psychologists have noted that imagery can be an effective medium for expressing difficult emotions. Social network sites like Instagram offer unprecedented opportunity for image-based sharing. In this paper, we investigate sensitive self-disclosures on Instagram and the responses they attract. We use visual and textual qualitative content analysis and statistical methods to analyze self-disclosures, associated comments, and relationships between them. We find that people use Instagram to engage in social exchange and story-telling about difficult experiences. We find considerable evidence of social support, a sense of community, and little aggression or support for harmful or pro-disease behaviors. Finally, we report on factors that influence engagement and the type of comments these disclosures attract. Personal narratives, food and beverage, references to illness, and self-appearance concerns are more likely to attract positive social support. Posts seeking support attract significantly more comments. CAUTION: This paper includes some detailed examples of content about eating disorders and self-injury illnesses.

This qualitative study examines privacy practices and concerns among contributors to open collaboration projects. We collected interview data from people who use the anonymity network Tor who also contribute to online projects and from Wikipedia editors who are concerned about their privacy to better understand how privacy concerns impact participation in open collaboration projects. We found that risks perceived by contributors to open collaboration projects include threats of surveillance, violence, harassment, opportunity loss, reputation loss, and fear for loved ones. We explain participants' operational and technical strategies for mitigating these risks and how these strategies affect their contributions. Finally, we discuss chilling effects associated with privacy loss, the need for open collaboration projects to go beyond attracting and educating participants to consider their privacy, and some of the social and technical approaches that could be explored to mitigate risk at a project or community level.

We examine how teens from an urban area in the Mid-Atlantic region of the USA regulate their use of technology. We framed our research using everyday life information seeking theory [43] and information ecologies [35]. Using a survey, audio and photo diary study, creative free response activity, and semi-structured interviews, we examine teens' perceptions of their everyday life technology use and factors that influence changes in that use, with a focus on understanding non-use, low use, and intentional self-regulation. We describe four factors impacting these practices, including local policies and access, affective factors, life stage and future goals, and relationships. We describe how shifting use practices function in the lives of these teens and discuss the importance of acknowledging teens' skills and preferences for supporting their technology use management.

Support seeking in stigmatized contexts is useful when the discloser receives the desired response, but it also entails social risks. Thus, people do not always disclose or seek support when they need it. One such stigmatized context for support seeking is sexual abuse. In this paper, we use mixed methods to understand abuse-related posts on reddit. First, we take a qualitative approach to understand post content. Then we use quantitative methods to investigate the use of "throwaway" accounts, which provide greater anonymity, and report on factors associated with support seeking and first-time disclosures. In addition to significant linguistic differences between throwaway and identified accounts, we find that those using throwaway accounts are significantly more likely to engage in seeking support. We also find that men are significantly more likely to use throwaway accounts when posting about sexual abuse. Results suggest that subreddit moderators and members who wish to provide support pay attention to throwaway accounts, and we discuss the importance of context-specific anonymity in support seeking.

In this multiple case study of two high schools in the USA, we use interview and focus group data to examine the experiences of teen-age students when they friend and interact with teachers, high school administrators, parents, and other adults on social network sites (SNS). We identify several types of teen-adult interactions on SNS, including finding information, community building, and mentoring online skills, and we connect these findings to literature on homophily and context collapse. We also report on social media norms and policies of the schools where our fieldwork was conducted. We discuss how organizational policies surrounding social media use can inhibit or reinforce the development of age-homophilous networks and thereby encourage or reduce opportunities for teen-adult interaction online. Finally, we conclude that boundary work associated with managing these complex social experiences, though awkward at times, can be an important learning experience for adults and young people alike.

One of the skills that comprise computational thinking is the ability to read code and reason about the hierarchical relationships between different blocks, expressions, elements, or other types of nodes, depending on the language. In this study, we present three new instruments for assessing different aspects of reading hierarchies in code, including vocabulary, reasoning, and fluency. One of these instruments is Nester, an interactive tool we have designed to elicit mental models about the hierarchical structure of code in computing languages ranging from HTML, CSS, and LaTeX to JavaScript and Lisp. We describe a lab study in which we administered these instruments to 24 participants with varying degrees of web development experience. We report findings from this study, including participants' ability to define, reason about, and manipulate hierarchies in code, and the errors and misconceptions that relate to them. Finally, we discuss avenues for future work.

We describe the design rationale and principles of a web authoring tool for beginner web developers called Snowball. We explain how this constructionist toolkit exposes content creators to computational features of web pages, enabling them to create meaningful artifacts while they move from content creation to basic coding. Finally, we discuss how we are instrumenting learning analytics in Snowball.

Many people are first exposed to code through web development, yet little is known about the barriers beginners face in these formative experiences. In this article, we describe a study of undergraduate students enrolled in an introductory web development course taken by both computing majors and general education students. Using data collected during the initial weeks of the course, we investigate the nature of the syntax errors they make when learning HTML and CSS, and how they resolve them. This is accomplished through the deployment of openHTML, a lightweight web-based code editor that logs user activity. Our analysis reveals that nearly all students made syntax errors that remained unresolved in their assessments, and that these errors continued weeks into the course. Approximately 20% of these errors related to the relatively complex system of rules that dictates when it is valid for HTML elements to be nested in one another. On the other hand, 35% of errors related to the relatively simple tag syntax determining how HTML elements are nested. We also find that validation played a key role in resolving errors: While the majority of unresolved errors were present in untested code, nearly all of the errors that were detected through validation were eventually corrected. We conclude with a discussion of our findings and their implications for computing education.

This paper provides first steps toward an empirically grounded design vocabulary for assessable design as an HCI response to the global need for better information literacy skills. We present a framework for synthesizing literatures called the Interdisciplinary Literacy Framework and use it to highlight gaps in our understanding of information literacy that HCI as a field is particularly well suited to fill. We report on two studies that lay a foundation for developing guidelines for assessable information system design. The first is a study of Wikipedians', librarians', and laypersons' information assessment practices from which we derive two important features of assessable designs: information provenance and stewardship. The second is an experimental study in which we operationalize these concepts in designs and test them using Amazon Mechanical Turk (MTurk).

The majority of American teens use social network sites (SNSs) but little is known about how they leverage their online social networks to find information. As part of a larger study on social media and information behaviors, we surveyed 158 high school students to learn about their online question asking and answering practices. We describe which teens are most likely to ask and answer questions, what they ask about, on which sites they ask questions, and how useful they perceive SNSs to be as information sources. When possible, we draw comparisons with findings in the literature about adult populations. We contextualize these findings using early insights from interviews and focus groups with 80 teens and discuss how perceptions of audience, privacy concerns, and self-presentation all play a role in teens' use of SNSs to ask and answer questions.

Findagrave.com and Ancestry.com are sites that support the cooperative creation of public historical resources. These sites of cooperative production have attracted tens of thousands and millions of contributors respectively, yet they embrace content standards, social norms, and models of editorial control that differ radically from the well-studied exemplar of Wikipedia. In this study, we investigated how Ancestry.com and Findagrave.com support production of historical resources through analysis of message boards and interviews with participants. We found that these sites are not only places for building a historical resource, but simultaneously serve as opportunities for public memorialization and familial identity construction. Notably, we found that contributors to these websites embrace the idea of familial oversight of biographical information in order to maintain high standards of quality, and they harbor a corresponding skepticism of the open editing practices that have become a hallmark of many open collaboration projects.

In this short paper, we describe the design of a new web editor for beginners called openHTML and our initial evaluation with children aged 10 and 11 in an after-school web-building workshop. Drawing on data from verbally administered surveys and participant observation, we identified three kinds of engagement with the workshop tasks: a homework orientation, an artistic orientation, and a social orientation. We describe the kinds of scaffolding that the children needed to complete their web pages, the places where they struggled, and translate these observations into implications for the design of a web editor for children.

Facebook is a global phenomenon, yet little is known about use of the site in urban parts of the developing world where the social network's users are increasingly located. We qualitatively studied Facebook use among 28 young adults living in Viwandani, an informal settlement, or slum, in Nairobi, Kenya. We find that to overcome the costs associated with Internet use, participants consolidated diverse online activities onto Facebook; here we focus on the most common practice--using Facebook to support income generation. Viwandani residents used the site to look for employment opportunities, market themselves, and seek remittances from friends and family abroad. We use our findings to motivate a design agenda for the urban poor built on an understanding that Facebook is used, with mixed-success, to support income generation. A key part of this agenda calls for developing ICT interventions grounded in users' existing practices rather than introducing new and unfamiliar ones.

Facebook use is pervasive in developed countries where computers, smartphones, high-bandwidth Internet, and electricity are ubiquitous. In this paper, we examine Facebook use in a country where social media participation is growing, but less developed technological infrastructures and uneven access to technology limit use. We conducted observations and 24 interviews at Internet cafés in rural Kenya. Our findings reveal how costs associated with using the Internet, limited access to computers and smartphones and unreliable electricity hinder online participation. We draw on these results to discuss the critical role of constraints in understanding social media use, to raise questions about broadening online participation and to highlight ethical issues researchers must consider when studying Facebook use in developing regions.

As part of a larger research agenda to explore web development as a context for learning computational literacy skills, we investigate errors people make while writing code in HTML and CSS. We report on a lab-based study in which 20 participants were video recorded as they completed coding tasks. We have applied the skills-rules-knowledge framework to segment this data by the cognitive causes of errors they made, and present a taxonomy of these errors. Our findings demonstrate how the skills-rules-framework can be used to analyze coding errors, provide insight about the origins of these errors, and suggest ways that the design of web development tools can be improved to support learning and practice with HTML and CSS.

We report on a study of the English edition of Wikipedia in which we used a mixed methods approach to understand how nested organizational structures called WikiProjects support collaboration. We first conducted two rounds of interviews with a total of 20 Wikipedians to understand how WikiProjects function and what it's like to participate in them from the perspective of Wikipedia editors. We then used a quantitative approach to further explore interpretations that arose from the qualitative data. Our analysis of these data together demonstrates how WikiProjects not only help Wikipedians coordinate tasks and produce articles, but also support community members and small groups of editors in important ways such as: providing a place to find collaborators, socialize and network; protecting editors' work; and structuring opportunities to contribute.

Traditional activities change in surprising ways when computer-mediated communication becomes a component of the activity system. In this descriptive study, we leverage two perspectives on social activity to understand the experiences of individuals who became active collaborators in Wikipedia, a prolific, cooperatively-authored online encyclopedia. Legitimate peripheral participation provides a lens for understanding participation in a community as an adaptable process that evolves over time. We use ideas from activity theory as a framework to describe our results. Finally, we describe how activity on the Wikipedia stands in striking contrast to traditional publishing and suggests a new paradigm for collaborative systems.

There is growing interest in computing courses for non-CS majors. We have recently built such a course that has met with positive response. We describe our design process, which includes involvement of stakeholders and identifying a context that facilitates learning. We present evaluation results on success rates (approximately 90% of the students earn an A, B, or C) and impact of the course on students over time (80% report that the class has influenced them more than a semester later).