This monograph highlights important findings and guidelines that have emerged from over a decade of research at the University of Oregon's Center for Educational Policy and Management (CEPM) concerning the continued professional development of school personnel. After a brief introduction, the booklet is divided into three sections. The first, "Foundations," introduces a framework for thinking about continued professional development. The framework identifies key factors in analyzing or designing a professional development program and introduces basic concepts. This is followed by a brief review of prevailing staff development practices. The second section, "Research and Development," consists of three chapters that describe CEPM-affiliated projects aimed at increasing the effectiveness, respectively, of teachers, programs, and the organization as a whole. Section 3, "Action," presents guidelines for district administrators in designing professional development programs and for principals in implementing them at the school level. The booklet closes with a discussion of challenges that lie ahead for professional development. A bibliography is included. (TE)