This monograph consists of 22 reprints of reports published since 1979 in the Middle School Journal's regular column "What Research Says to the Practitioner." Each report synthesizes research studies related to effective implementation of middle school programs and concludes with a list of references. The contents are divided into two main sections: "Organization of the Middle School" and "Teaching Middle School Students." Section one covers the topics of school and principal effectiveness, teacher behavior, thinking and stress, and student promotion and retention. Section two includes reports on motivating students, peer relationships and classroom management, ability grouping, diagnostic prescriptive teaching, classroom time, development of student attitudes and problem solving skills, critical thinking, the teacher's effect on pupil self-concept and related school performance, instructional questions, and computer-assisted instruction. A third short section, "Needed Research," presents the results of a survey taken of 400 members of the National Middle School Association (NMSA) to identify priorities for future research in middle school education. (IW)