This study examines eight exemplary pre- and in-service principal development programs. The programs were chosen both because they provide evidence of strong outcomes in preparing school leaders and because, in combination, they represent a variety of approaches with respect to their designs, policy contexts, and the nature of partnerships between universities and school districts. Pre-service preparation programs were sponsored by four universities: Bank Street College, Delta State University, the University of Connecticut, and the University of San Diego working with the San Diego City Schools. In-service programs were sponsored by the Hartford (CT) School District, Jefferson County (KY) Public Schools (which included a pre-service component), Region 1 in New York City, and the San Diego City Schools. In several cases, pre- and in-service programs create a continuum of coherent learning opportunities for school leaders. To understand how the programs operate and how they are funded, the authors interviewed program faculty and administrators, participants and graduates, district personnel and other stakeholders; reviewed program documents; and observed meetings, courses, and workshops. Findings include: (1) Exemplary programs can produce leaders who engage in effective practices; (2) Exemplary pre- and in-service development programs share common features; (3) Program success is influenced by leadership, partnerships, and financial supports; and (4) State and district policies influence program designs and outcomes. Appended are: (1) Principal Survey Methods; (2) Instrumentation for Fieldwork and Survey Data Collection; (3) Instrumentation for Study of Costs of Principal Professional Development Programs; and (4) Cross-State Comparisons of Principals' Survey Responses. (Contains 8 figures, 29 tables and 19 footnotes.) [This paper was written in collaboration with Margaret Barber, Kimberly Dailey, Stephen Davis, Joseph Flessa, Joseph Murphy, Raymond Pecheone, and Naida Tushnet. This paper was commissioned by The Wallace Foundation. For Case Study Summaries, "Preparing School Leaders for a Changing World: Case Studies of Exemplary Programs. School Leadership Study. Case Study Summaries," see ED533008. For Review of Research, "Developing Successful Principals. School Leadership Study. Review of Research, see ED533009.]