The authors trace changes in conceptions of special education teacher quality and preparation in response to developments in special education research, policy, and practice. This developmental arc is a backdrop for understanding contemporary special education practice and charting future directions for preparing special education teachers. Federal policy, and recent research on teaching and learning, and the response-to-intervention (RTI) movement require a shift in thinking about how to prepare quality special education teachers and the expertise they need to be effective. To function effectively in RTI and fulfill federal highly qualified teacher requirements, special education teachers must master an increasingly comp lex knowledge base and sophisticated repertoire of instructional practices. The authors contend that preservice preparation is inadequate for this purpose and that preparation for special education teaching should build up on an existing knowledge base and demonstrated competence in classroom practice.