This paper deals with an approach to school system change -- the establishment of a change agent team to plan for and manage specific changes and to facilitate and perpetuate an innovative climate. It presents case studies of change agent teams in three Wisconsin school systems. A model for change agent team planning and action -- problem diagnosis, strategy planning, strategy activation, and result evaluation -- is described. The activities of the teams and their colleagues are related, and an evaluation of the interventions based on systematic data is included. (Author)