Focusing on 67 studies written since 1970, this report reviews the literature on the topic of school effectiveness to discover those characteristics most in evidence in effective schools and classrooms. Research on effective schools has concentrated on such topics as school climate, the role of leadership, students' preschool experiences, and class size. School climate studies, for example, have examined the high expectations of effective schools and their students' acceptance of school norms. Leadership studies have concluded that the principal sets the tone of success in effective schools by emphasizing high expectations, a congenial atmosphere, reading skills, and careful evaluation of student progress. Students who attend preschools, it has been found, score significantly higher in achievement than others and so contribute to the effectiveness of their later education. Class size, however, has a debatable influence on student achievement. Research on effective classrooms has concentrated on such topics as teacher expectations, individualized instruction, and the role of time in learning. High expectations produce high achievement, it has been found, and most teachers are most effective in working with smaller groups of students. On the role of time in learning, studies have shown that the more time allocated to a content area, the higher was the academic achievement; students spending much time engaged in activities that promote learning are also higher achievers. (JW)