The leadership-for-learning project described in this article is supported by a grant from the Wallace Foundation and implemented through a partnership of faculty in the Department of Educational Leadership and Policy Analysis at the University of Wisconsin-Madison and faculty at two other universities in the state, the Department of Public Instruction, the Association of Wisconsin School Administrators, and administrators and teacher leaders (department chairs and other teacher leaders) in five urban school districts. The primary objective of the collaborative project was to develop an aligned system of leadership development in the state with particular attention to building and strengthening instructional leadership capacities to advance learning for all students in 15 urban high schools. The study reported in this article is part of a larger study of the leadership- for-learning project (see, e.g., Kelley & Salisbury, 2013; Klar, 2013). This article focuses on the professional development practices that support the emergence of distributed instructional leadership (DIL) in six urban high schools. Two major research questions are addressed: (1) What do the professional development experiences of leadership teams in six urban high schools tell us about professional development as a major approach for building DIL? (2) What is the content of professional development (knowledge, skills, and dispositions) for building DIL capacity in urban high schools? The findings from this study indicate that professional development focused on building DIL capacity in six urban high schools is a major strategy for realizing this whole school improvement initiative. The findings also suggest that advancing DIL in urban high schools is a complex and challenging change process requiring the acquisition and application of four categories of professional knowledge--ethical, propositional, procedural, and pragmatic.