Effective schools have staffs that stress the importance of educational goals and have a well-defined mission. They also clearly communicate the expectation that all students can and will reach the stated goals. Reviews of studies of exemplary schools find that the principals express high expectations for both teacher and student performance, while the teachers have high expectations for their students. Effective schools have a climate conducive to student attainment, whereas declining schools project a negative climate and a belief that students cannot attain educational goals. An orderly learning environment is another important factor in effective schools and further reflects a positive school attitude and climate. The most consistent finding in school effectiveness research is the importance of the principal's strong leadership role. The principal sets the tone for the school and reinforces the positive school climate. Since schools are distinguished by a complex set of cultural processes, the modification of this "culture" in ineffective schools is not a simple matter. One effective method for improvement is the use of organizational development techniques specifically designed to alter the norms of an organization. Behavior modification techniques can also be used to alter a school's norms. A body of literature geared to the "cultural" view of school change has recently emerged; "Creating Effective Schools" by Wilbur Brookover is recommended to school principals as a source of guidelines for improving a school. (MD)