"Peer Teaching in Permanent Project Teams (PT('2))" is an instructional technique designed to encourage students to teach each other. The technique is based on concepts from the literature on "Group Dynamics." Data from 288 students in eight experimental (PT('2)) and eight match control sections of an introductory zoology laboratory course were analyzed. Results indicate that PT('2) resulted in increased cooperativeness and academic performance. Results were inconclusive with respect to the effect of PT('2) on the quantity and quality of peer teaching and student satisfaction. Implications for many educational and training situations are also discussed.