Many assessment experts believe it is essential to develop faculty-driven assessment tools in order to engage faculty in meaningful assessment that can improve student learning. Tennessee Technological University (TTU) has been involved in an extended effort during the last ten years to develop, refine, and nationally disseminate an instrument to assess critical thinking that meets this criterion. The "Critical Thinking Assessment test" (CAT) was developed by faculty from a wide variety of institutions and disciplines, with guidance from their colleagues in the cognitive/learning sciences and assessment. In this article, the authors discuss the objectives of the critical thinking test and its features. They examine the validity of the CAT by comparing student performance on the test with other measures of academic performance and measures that might reveal critical thinking skills. (Contains 6 resources.)