Reports on over 600 research studies which compare learning in cooperative, competitive, and individualistic goal structures have been collected at the Cooperative Learning Center at the University of Minnesota. From these studies it has been concluded that having students work together is much more powerful than having students work alone, competitively, or individually. Some of the findings from these studies are presented and discussed. For example, students are motivated to learn material when they work together and also develop more positive attitudes while working together. These and other findings suggest that science teachers should structure much of their science class in small, heterogeneous, cooperative groups. (JN)