The current research on the "characteristics of effective schools" suffers from a lack of any sound theoretical foundation. In order to establish such a foundation, researchers used the methodology of clinical analysis to determine the goals, purposes, and beliefs underlying the overt behavior patterns found in the effective school improvement projects being conducted in four states and at least eight Connecticut school districts. The characteristics of effective schools found through this process consisted of isolated, if not unrelated, variables. Analysis revealed a common theoretical basis for behavior across three effect domains: school effects, teacher effects, and student effects. The analysis also suggests listing overt behaviors as a method of identifying what actions might be taken at the school level to increase student achievement. Clinical analysis of one effective school characteristic, the opportunity to learn, supports a theory stating that the principles of behaviorism can be built into the school and the classroom and can ultimately be brought to bear on the student. (Author/PGD)