In 1996 the National Commission on Teaching and America's Future released a report titled What Matters Most: Teaching for America's Future. The report identified seven barriers to school reform: (a) low expectations for student performance; (b) the absence of enforced standards for teachers; (c) major flaws in teacher preparation; (d) inadequate efforts at teacher recruiting; (e) inadequate induction for beginning teachers; (f) inadequate professional development opportunities and few rewards for knowledge and skill; and (g) schools that are structured for failure rather than success. The first three of these barriers are focused directly on teacher preparation. Among the commission's recommendations were calls for the improved assessment of teachers and students. In particular, the call was for a more explicit focus on defining, measuring and reporting on the outcomes achieved by teachers and their students. States such as Oregon and Colorado now require preservice teachers to demonstrate their proficiency in moving students toward stated educational objectives. One way institutions and states require preservice teacher proficiency to be demonstrated is called Teacher Work Sample Methodology (TWSM). TWSM was first developed and studied in Oregon by Schalock (1998). This paper describes the political conditions that have made TWSM a graduation requirement in some states and reviews the findings from TWSM in general education. The findings are reported in terms of student gain scores and pre-post distributions of student learning from teacher work samples. Implications are discussed in relation to findings of the National Commission on Teaching and America's Future and the policies of the National Council for the Accreditation of Teacher Education (NCATE). Keyword(s): professional preparation, research