To provide administrators and teachers with a set of essential elements and principles to consider in using inservice programs for school improvement, this document presents a model comprised of 27 dimensions identified as important elements of effective inservice programs. These dimensions were identified through a review of the research literature on basic skills instruction at the elementary school level. (Appendix A briefly reviews the sources providing this research.) A second literature review identified four inservice experiments that used these dimensions to improve students' basic skills achievement. (Appendix B briefly describes these experiments.) Following a foreword and introduction, a table summarizes the findings concerning these dimensions--listing each element, the effective practice associated with each element, and the research validating the effectiveness of these practices. The four types of research used include basic skills experiments, implementation research, inservice research, and survey research. The bulk of the document expands on these aspects of each dimension, with the dimensions divided into the following six categories: teacher objectives, student objectives, delivery systems, organizational context, governance, and selection and evaluation. To illustrate how theory is transferred into practice, case studies of three successful school district staff development programs are provided. A bibliography lists 56 references. (DCS)