A growing body of literature has highlighted the affordances of distributive forms of instructional leadership as a means to broaden and deepen instructional leadership capacity within schools. Yet, specifically how the capabilities of such key leaders as high school department chairs can be fostered to realize enhanced instructional capacity remains less well understood. In this article, I examine the efforts of principals in three urban high schools to foster the leadership capacities of their department chairs as a case of distributed instructional leadership. Data for the study were gathered from interviews, participant observations, and analyses of documents collected during a 2-year Leadership for Learning grant funded by the Wallace Foundation. The findings illustrate the crucial role that the principals played in redefining leadership roles, responsibilities, and structures; providing individual and team learning opportunities; and connecting the work of the department chairs to school and district instructional improvement efforts. I conclude with implications for practice and further research.