Leadership development in the public sector needs more of an emphasis on collaboration. Today's public leaders must be effective boundary-crossers, working in partnership with organizations across jurisdictional and sectoral boundaries. This paper identifies some key competencies of collaborative leadership that go beyond those already identified for organizational leadership. The purpose is to offer a starting point for discussions of how public leadership development efforts should be augmented in order to reflect the reality of collaborative governance. Important competencies for collaboration include personal attributes such as systems thinking and sense of mutuality; skills such as strategic thinking and group facilitation; and behaviors such as stakeholder identification and strategic issue framing. Developing collaborative behavioral competencies requires an inside-out approach that goes beyond learning tools and addresses the fundamental personal attributes that facilitate collaborative action.