A brief literature review and a report on two studies of change implementation in schools indicate that "directed development," in which experts give help directly to classroom teachers, is the most effective implementation strategy. The author's literature review traces research on program implementation from a 1975 Rand report stressing "mutual adaptation" of school and change programs, through reports on attempts to implement mutual adaptation, to a reanalysis of the Rand data that instead emphasizes directed development. The paper then summarizes two studies evaluating change implementation programs that used directed development. For the first study, covering the School Improvement Program carried out by the New York City Public Schools in 24 public and private schools, the author describes the schools, the project, the variables studied, and the evaluation findings from interviews and a questionnaire survey. The second study involved implementation of the Direct Instruction Follow Through model in one school district. A project description precedes a summary of interview results from the study. Among the author's findings are that the studies support using experts to give teachers direct assistance that results in student achievement gains. (RW)