Thirteen of 14 secondary schools increased their educational effectiveness by participating in a long-term, 12-step change process with two significant features: several measures were applied to develop a picture of each school's effectiveness, and student involvement in the process was considered essential. Schools were categorized by effectiveness using measures of socialized behavior, academic achievement, school culture and climate, and participation by teachers and students in voluntary activities. The 12-step process undertaken by the schools involved (1) acceptance of leadership responsibility by administrators, (20 appointment of a change team including teachers and administrators, (3) team review of school effectiveness, (4) appointment of a student leadership group, (5) planning for a leadership retreat, (6) participation in the retreat, (7) creation of task forces to address specific problems, (8) establishment of task force meeting agendas, (9) planning of inservice training, (10) documentation of changes in effectiveness, (11) establishment of annual leadership team elections, and (12) a year-end review. The school effectiveness program works primarily because it alters the informal social agreements made among students, teachers, and administrators about how members of each group are expected to act. This leads to new social agreements, norms, or understandings about priorities for the schools. (PGD)