In this video I introduce the control source and unit test announcement from MIX, and then walk you through: -exploring the Silverlight 2 Beta 1 control source code, unit test and unit test framework download -using Visual Studio 2008 to run the control unit tests -adding the Exclusive attribute to narrow the test(s) that run in the browser when analyzing tests -running the tests in Firefox -running the tests in Expression Blend 2.5