This longitudinal study of 320 US schools explored the importance of the principal to the development of programs of school, family, and community partnerships. Schools rated the degree of support from the principal for school-wide efforts of family and community involvement and provided data on principal turnover. Analyses also explored other essential elements of partnership program success including teamwork and external support variables. The regression analyses indicated significant and positive relationships between principal support and partnership program quality in 2002. Principal turnover failed to predict variation in program quality. The results suggest the importance of engaging the principal in partnership efforts; developing strong support for partnerships among parents, teachers, and community members; and continually expanding and evaluating the work of the partnership team to promote student success and development.