Decades of research have documented the positive impacts of cooperative learning on student success: increased learning, retention through graduation, improved critical thinking, and intrinsic motivation. One cooperative teaching technique, however, has received relatively little attention. In the two-stage cooperative, group, or "pyramid" exam students first take an exam individually--as in traditional testing--and then take the same exam together with their learning group, with the exam grade being a weighted combination of their individual and group scores. This approach uses the exam itself not only for evaluation, but also as a learning tool. Although some researchers have studied group exams, they have not isolated the impact of group tests from individual achievement--an important omission. Using data from a mass lecture introductory sociology course, I found that holding individual achievement constant the group exam process significantly increased learning both for students who knew the material initially and for those who did not. This suggests that cooperative exams not only enhance learning but also allow for the process and form of testing to become more closely linked to the process and form of teaching and learning. (Contains 2 tables, 2 figures and 8 footnotes.)