This publication is designed to show principals how to improve staff development strategies. It begins by laying the foundations for teacher development. The first chapter explains what is known about teaching and identifies four general groups of teachers: productive teachers, who are highly motivated and skilled; novice teachers, who are still mastering the basic skills of teaching; marginal teachers, experienced teachers, who still demonstrate serious deficiencies; and passive teachers, who are competent but unmotivated. The second chapter explains the kind of work environment that all teachers and principals should have, termed a "learning community," in which growth and development flourish in a collaborative culture. Chapter 3 explains how to organize that learning community for individualizing developmental services. However, rather then prescribing one set of structures for all schools, the chapter explains the basic principles needed and presents a process that can be used in developing homegrown structures. Chapters 4,5,6, and 7 explain how principals can foster the development of the four groups of teachers identified. Each of these chapters begins by describing the characteristics and needs of the group considered, then explains what services are needed and how they can best be provided. Chapter 8 focuses on the nonteaching professional staff--the nurses, librarians, counselors, social workers, and classified staff. The final chapter discusses ways principals can develop the support resources needed to accomplish the goals identified. (Contains 74 references.) (ND)