This book is about a set of alternatives to the traditional instructional system: cooperative learning methods. These are techniques that use cooperative task structures, in which students spend much of their class time working in 4-6 member heterogeneous groups. These learning methods also use cooperative incentive structures, in which students earn recognition, rewards, or (occasionally) grades based on the academic performance of their groups. Research on cooperation has been conducted since the beginning of this century, although classroom research on practical cooperative methods began in the early 1970s. There are several cooperative learning methods, which vary in almost every particular. What unites them is their applications of the basic principles of cooperative incentive and task structures to achieve cognitive as well as non-cognitive goals in typical classrooms. The cooperative learning researchers are also united in their belief that the optimal instructional system may not be found within the range of variation among traditional classrooms, but must be created based on sound psychological and pedagogical theory and rigorously evaluated in classroom practice. This book presents the theoretical basis of cooperative learning, the methods based on this theory, and the results of evaluations of these methods. (JMK)