Findings of a case study that examined ways in which an urban high school principal successfully improved an urban high school are presented in this paper, with attention to social interaction processes. Data were collected through interviews with the principal and 10 teachers and through questionnaires administered to the 10 teachers. Findings suggest that the principal's leadership style was characterized by the use of opportunism, persistence, teacher rapport, and resource procurement. A distinction was made between the principal's mission (survival of the school) and vision (academic renewal). The principal also acted as an entrepreneurial program manager and a coordinator. By creating a climate of academic achievement and high student expectations, he demonstrated that principal behaviors are directly related to instructional effectiveness. Three tables and one figure are included. (Contains 32 references.) (LMI)