Cooperative learning (CL) is a well documented pedagogical practice that promotes academic achievement and socialization, yet many teachers struggle with implementing it in their classes. This study reports on the perceptions of 10, middle-year teachers who implemented cooperative learning in a unit of work across two school terms. Data from the interviews indicated that while the teachers had positive experiences with CL, a number encountered difficulties with implementing it in their classrooms. Issues identified included students socializing during group activities and not working, managing time effectively, and the preparation required. Other issues that the teachers identified as being important for successful group work included the composition of the groups, the task the group was to undertake, the social skills training needed, and the assessment of the learning that occurred in the group.