Philanthropy is private capital directed for public good, so it is especially important that it be well invested. Changing outmoded or dysfunctional systems takes persistence, time, and vigilance, and it is often philanthropy's role to act as "patient" capital that embraces the longer time horizons required to bring social-impact ventures to maturity. Individual philanthropists and foundation leaders will share insights about their successes, best practices, and the importance of committing to a long-term vision.