The Technical Assistance Base (TAB) was established to provide the National Diffusion Network (NDN), a nationwide federal effort at school improvement, with the technical support needed to help NDN members strengthen their knowledge and capacities. This document reports on TAB's accomplishments over its first three years. Section one gives an overview of NDN, briefly reviews the literature on technical assistance, and recounts the historical background and early evolution of TAB. Section two discusses TAB's objectives, assumptions, organizational structure, and procedures. TAB's achievements are described in section three, including the topics on which technical assistance was given, the number and types of clients served, the workshops and other modes used to deliver TAB services, and the level of client satisfaction with TAB. Section three also gives detailed lists of TAB workshops and group sessions and discusses TAB's emphasis on evaluation, leadership, rural schools, coordination with higher education, computer utilization, and career education. Section four offers a brief summary of the preceding three sections. Appended to the report are TAB activity report forms, a task analysis outline, and TAB needs assessment surveys. (Author/RW)