A strategy for assessing the skill needs of principals and for training them to assume effective instructional leadership is outlined in this paper. A school production model of instructional leadership, supported by research, is presented; the model emphasizes orientation toward specific goals of school productivity and suggests ways to analyze results. A diagnostic instrument designed to assess training needs of principals is described, and the course of its development is discussed in detail. The results of the instrument confirmed that principals view instructional leadership tasks as important and that they feel unprepared for jobs emphasizing instructional leadership. Analysis of research produced 10 competency statements, grouped into 4 clusters. The organizational planning cluster includes schoolwide goal setting, work group performance, and individual staff performance. The staff management cluster includes staff development, clinical supervision, work group development, and quality control. The program management cluster consists of instructional programming and resource development, while the achievement assessment cluster focuses on school evaluation procedures. A figure illustrating the model, tables summarizing the data, and survey instruments are provided. (FWR)