The realities of teacher preparation are not self-evident. Researchers, educators, and policymakers need a framework to describe what goes on in teacher education programs and to determine how they do or do not measure up as preparation for teaching. This paper presents such a framework. The framework rests on a conception of the central tasks of teaching and the major sources of influence on teacher learning during formal preparation. The framework allows us to relate empirical realities of learning to teach with a view of worthwhile ends and defensible means for teacher education. To show how the framework helps in describing and appraising opportunities to learn and learning outcomes, the report presents illustrative findings from a longitudinal study of teacher preparation and learning to teach. (Author)