Many development teams have adopted "agile" methodologies to manage change and to improve software quality. These methodologies promote continuous integration as a practice to build and test software products incrementally as new features are included, bugs are fixed, and code is refactored. So how does Visual Studio® 2005 Team System and Team Foundation Server facilitate the process of agile development and continuous integration? This article answers that question by creating an example project using agile concepts such as test-driven development (TDD) using the new unit testing features in Visual Studio 2005 Team System. After the project is completed, I'll show how to create a team project using Team Foundation Server and use this technology's extensibility features to build a custom Web service that enables continuous integration to build the application as code is checked into source control.