The authors suggest that the gap between common evaluation practice in teacher preparation and the consensus reform goal of high levels of student learning for all students is an impediment to reinventing teacher preparation, professional development, and the professionalization of teaching. In the context of Oregon’s six-year-old educational transition to a standards-based design for schools and schooling, prospective teachers in Oregon have, since 1989, been required to design, develop, and implement “teacher work samples” as credible evidence of their effectiveness in fostering student learning as a condition for recommendation for an initial teaching license. This article describes teacher work sample methodology and evidence for its reliability and validity in evaluating the performance of prospective teachers. In short, this article describes a methodology that responds to one critical part of the National Commission on Teaching and America’s Future’s challenge to reinvent teacher education and improve student learning.