In the third volume of this 10-volume report, 3 causal models of the school improvement process are presented and are used to identify outcomes of implementation and the factors influencing success. The first model predicts individual-level outcomes as a function of the magnitude of expected changes in instructional practice and the time spent on practice-related activities. The second model predicts school-level outcomes by projecting causal or predictive links between demographics, administrative context, practice-specific assistance, school-level outcomes, and individual-level outcomes. (Another predictive chain is posited between demographics, teaching context, and individual outcomes.) The third model predicts external facilitator assistance as a function of his or her position. External facilitators must choose (1) whether to work primarily with administrators or with teachers, (2) whether to emphasize "front end" or "back end" assistance, and (3) whether to concentrate on evaluation or continuation/extension activities. Findings obtained through the application of these models indicate factors that contribute to the success of an implementation effort. Implications for school and district personnel, external facilitators, and state and federal policymakers are discussed. (TE)