This study examined the long-term effects of providing a research-based approach to classroom management through a two-phase staff development process. The process was designed to promote teachers' ability to establish and maintain effective classroom groups. Teachers' uses of group-development principles, cooperative-learning strategies, and related student outcomes were investigated. Analysis of interviews and observational data suggested the possibility that the teachers' motivation for learning to manage instruction through cooperative groups was critical to the differences in observed performance. Teachers who used group-development strategies primarily as a means of classroom management were less successful than teachers who used group-development strategies to increase student responsibility, accountability, and productivity. Results of the study indicated the importance of having a teacher support group during initial implementation of new approaches to instruction. Colleagial problem solving proved to be a key factor in the success of the project. It also appeared that staff development programs that allow both direct and indirect contact with a teacher educator can be successful in accomplishing implementation goals. (JD)