Parallel efforts in principal evaluation and educator preparation are prompting new conversations among states, higher education programs, private foundations, and professional associations about strengthening school leadership development pipelines. A strong school principal pipeline has many elements, but each element supports the evaluation and development of current and future school principals; these elements include common, aligned leadership standards; performance measures; and professional learning supports. Taken together, a strong principal pipeline guides and grounds principal recruitment, preparation, hiring, evaluation, and support (Turnbull, Riley, & MacFarlane, 2013).School districts and principal preparation programs both have separate but related roles in improving principal pipelines; however, because separate organizations are responsible for supporting principals' careers, P-20 partnerships or state agencies coordinate principal pipeline improvement efforts. In this "Ask The Team," the authors highlight state activities and pertinent research on principal preparation, specifically state efforts to measure principal preparation program effectiveness. State efforts to create models for leadership program accountability face numerous methodological challenges. To inform collaborative efforts across a variety of policymakers and stakeholders, they reviewed information on principal preparation accountability models, examined existing reports on pilot approaches in states, and identified existing partnerships that are tackling this challenging work. Further, they offer examples as starting points for discussions on principal preparation program effectiveness, continuous improvement, and accountability.