Cooperative learning is a well-known instructional technique that has been applied with a wide variety of subject matter and a broad spectrum of populations. This article briefly reviews the principles of cooperative learning, and describes how these principles were incorporated into a comprehensive set of cooperative learning activities for a CS1 course. In each activity, specific roles are assigned to group members in order to highlight important concepts and to enhance the overall functioning of the group. The group processing is followed by a whole-class debriefing led by the instructor, which works in tandem with the group activity to help students improve their understanding of the material. The effectiveness of these cooperative learning activities was assessed in a series of educational research studies which spanned three academic years and included two different instructors. The results of these studies show statistically significant benefits from the cooperative learning approach, both overall and for a broad range of subgroups of students. The article concludes with suggestions for faculty members who may want to use these cooperative learning activities in the classroom, or to develop their own activities along similar lines.