This report presents a conceptual framework for the mission of the National Institute of Education (NIE) Research and Development Center for Teacher Quality and Effectiveness. Several important issues that should be the focus of the Center are identified, and the theoretical foundations to guide the research and development activities to study these issues are discussed. Also outlined is the role that the Center should have in assuming national leadership in the study of teacher quality and effectiveness, and the importance of developing new knowledge and perspectives that can inform the development and implementation of policy and can be taken and used by practitioners to improve their life, work, and productivity as teachers. The developers of this conceptual framework examined a broad range of popular, professional, and scholarly publications; consulted widely with policymakers and pracitioners; and undertook a survey of representatives of various education interest groups. The central issues that the Center should be engaged in are listed and discussed, including: (1) to attract and retain teachers; (2) to continuously enhance the competence of teachers who are recruited and who are currently in the profession in ways that increase their effectiveness; (3) to establish conditions in the workplace that facilitate the effective use of that competence; and (4) to motivate teachers to do their best and improve their practice. (CB)