This paper offers a comprehensive approach to creating a data base on learning to teach. It is organized chronologically around a learning-to-teach continuum. The first section deals with the pretraining phase, before prospective teachers even realize they are learning things that will shape their future teaching. The second section looks at the preservice phase, when future teachers undertake their formal preparation. The third section examines the induction phase, which coincides with the first year of teaching. The fourth section examines the inservice phase, which covers the rest of the teacher's career. Despite the limitations of the knowledge base, this broad perspective enables assessment of the relative contribution of formal and informal influences on teachers' learning. Three general assertions are developed in this paper: (1) Formal arrangements for teacher education and training do not fit with what is known about how teachers learn to teach and how they improve their teaching over time; (2) Informal influences figure more prominently in learning to teach, but often have miseducative effects; and (3) Creating more appropriate arrangements to support teachers' learning involves changing not only what educators do but also how they think about learning to teach. (Author/JD)