This report describes efforts to develop and implement a technique for using information on school performance as a tool in improving planning and management within a large urban school system. The Urban Institute and the Atlanta schools are attempting to demonstrate a technique for grouping schools on the basis of their student composition, comparing performance among similar schools, and then using the results in planning new programs and in assessing and restructuring existing educational activities. The method involves a means of identifying groups of schools which serve similar student populations and in which performance is therefore expected, a priori, to be similar. These groupings provide the framework for comparing relative performance, both within a single group and among groups, as a means of determining what is happening in a large complex school system. The technique focuses on outputs--on the changes that are occurring as a result of exposure to the educational process. The classification technique focuses on the school as the unit of observation, since it, rather than the pupil or the project, is the basic administrative unit in a local school system. Finally the classification techniques relies primarily on data which is already at a central location in the school system. (Author/JM)