In the last decade, research has shown major changes in the role and responsibility of the school administrator (Behling 1981; Curran 1982; Miller 1982; Shoemaker and Fraser 1981). This research portrays the principal as the key individual in facilitating school improvement. Equally important, he or she is seen as an instructional leader rather than a manager of buildings and people. In this new role, the administrator works with the teacher to improve instruction in order to increase student achievement. Additional research (more than 600 studies) has begun to document that cooperation is one of the most powerful ways to increase achievement, stimulate cognitive development, increase self-esteem, improve interpersonal relationships, and promote liking for school (Johnson and Johnson 1989; Slavin 1986). When these two bodies of research are scrutinized, some striking implications emerge about the theory and purpose of supervision. Administrators who understand the research dealing with cooperative learning (Johnson, Johnson, and Holubec 1986; Slavin 1986) and are committed to supervision as a primary function of instructional leadership will find that supervision of teachers who use cooperative learning can be exciting and challenging, if substantially different from direct supervision. There are some basic questions that emerge for the supervisor: What is the fundamental difference between classrooms using cooperative learning and traditional classrooms? What do I need to know to be an effective supervisor of teachers who use coopera-