Like many software companies, Microsoft has been doing distributed application development for many years. However, recent changes in the market have altered the rules, both in terms of customer expectations and programming models for ubiquitous interconnected smart devices. These changes have provoked two dramatic shifts in the way we develop software. The first is the creation and use of the .NET Framework as a simple, secure, and robust platform for device-independent software development, data manipulation, and communications. The second is an agile yet highly disciplined approach to designing, testing, implementing, and verifying our software which presumes all bugs are unacceptable and must be found and fixed early before they impact internal groups, external partners, and eventually our customers. This paper discusses the nature and impact of these two dramatic shifts to the development practices at Microsoft.