Case studies of five urban high schools illustrate some important factors that appear to be crucial in determining whether or not reform efforts are implemented. Among these factors are the following: (1) teacher participation; (2) collegiality among staff members; (3) shared belief that change can occur; (4) leadership by the principal; (5) sharing of power and vision among staff; (6) a program that is congruent with the vision, and developed from a coherent set of ideas and beliefs about education; and (7) some early successes in implementing the program. Common problems during implementation include those with the environment, with people, and with the program. When principals attack problems with a repertoire of coping strategies, including a variety of vigorous managing and capacity-building interventions, there is greater likelihood that the school improvement program will be integrated into the school's overall operation. These case studies illustrate particular ways that secondary school principals can involve other staff members in the reform effort. (MLF)