The Social Innovation Fund (SIF) is a groundbreaking, evidence-based approach to finding, improving and growing promising community solutions. This paper is part of a series designed to share information, best practices, and lessons learned from the development and implementation of the SIF. It provides an overview of the SIF initiative, an explanation of the SIF’s innovative learning strategy, a description of SIF-supported interventions (programs that address social and community challenges) and evidence of their effectiveness as well as the rigorous process used to evaluate SIF-funded programs.