This report was funded to answer the following questions using a series of interviews, research, and findings from a meeting of 45 evaluators and program officers with leadership development expertise, hosted on October 2014 at the Annie E. Casey Foundation: What are the key elements of leadership development approaches that are contributing to measurable progress on significant social problems? What evaluation approaches are being used or developed to successfully measure and document the impact of leadership development that results in large-scale change? What opportunities exist to replicate, spread, adapt, or apply lessons from these models to increase the impact of leadership development programming and investments?