The major purpose of the research reported here was to determine how teachers from middle school to high school levels acquired their understanding of cooperative learning, how they used it in the classroom, and how they kept students accountable for performance. Eleven teachers were interviewed and observed in five disciplines (language arts, mathematics, physical and health education, science, and Spanish). Teachers gained their knowledge of cooperative learning from coursework, peers, and professional organizations. Cooperative learning was primarily used for completing worksheets or textbook-type assignments, reviewing for tests, or reviewing homework. Typically, the teachers assigned students to groups to maintain a balance of abilities; they assigned roles to students and expected students to know their roles, but students often did not know what they were expected to do in their roles. Higher level thinking was observed often, but seldom seemed to be a primary objective. Teachers held cooperative groups accountable for completing tasks together and submitting the group's assignment. Usually a combination of group and individual grades was assigned, or individual grades were assigned with some extrinsic reward for the group. The classroom observations indicated that the teachers were generally not very "risk taking" in their use of cooperative learning, but that they were successful in the strategies they used. A cooperative learning interview form and an observation form are appended. (JDD)