An ethnographic study uncovers the work of nightclub DJs, which extends far beyond the act of mixing tracks to also encompass collecting music, preparing for performances, and promotion and networking. We reveal how DJs value vinyl and digital formats in different ways, acquire music through 'crate digging', prepare physical and digital crates of music before gigs, and how these underpin improvised selections during their performances. We document how DJs interact with promoters, venues, dancers and other DJs, revealing an etiquette that governs how they select and share music, and manage an ongoing tension between revealing and hiding metadata so as to maintain a competitive edge. We raise implications for technologies to support DJs, while also shedding light on previous studies of music consumption and sharing in other settings.

An ethnographic study of Irish music sessions in pubs elaborates the collaborative work involved in making traditional music. Central to this distinctive achievement is the sequencing of tunes so that they hang together and combine to form discrete "sets", which rely on a shared knowledge of musical repertoires. Our study shows how musicians develop this musical knowledge through the use of digital resources and social networks. It also reveals how musicians construct and make use of various paper props to help bring their knowledge to bear in the actual in vivo course of a session so as to maintain the moral order of making music together in a demonstrably traditional way. The social demands of musical "etiquette" sensitise CSCW to the need to design technologies to support the "situated discretion" that is essential to traditional practices. We elaborate this notion through a discussion of requirements for technologies that bridge between online resources and the collaborative sequencing of tunes during performance.