This guidebook discusses cooperative learning at the middle school level and provides lesson plans that use cooperative learning techniques in various subject areas. Part 1 details three classroom organizational options and the elements of cooperative learning; examines the major types of cooperative learning; reviews the importance of developing the social skills needed in conjunction with cooperative learning; and provides suggestions for initiating cooperative learning in the classroom. Part 2 contains 52 lesson plans in art, mathematics, music, reading/language arts, science, and social studies, each of which was submitted by active middle school teachers. Each lesson plan includes a clear description of the subject to be taught and the expected learning outcome, a description of the lesson procedures, and the materials necessary to conduct the lesson, many of which are reproducible. (MDM)