Testers perceive developers as cowboys interested in building cool features using the latest technologies and solving the hardest problems which, incidentally, might solve a customer problem. Developers think that testers prevent cool features from release by wasting time running and re-running arbitrary sets of tests and filing often useless bugs. Too often developers and testers work against each other which reduces application quality and ultimately results in a poor product. During development of Microsoft Visual Studio 2010, we took a very different approach, eliminating the walls between test and development and building a real partnership on behalf of our customers. In this session, we discuss the successes and failures of our approach, its impact on our products, and how we will try to improve the approach in the future.