The article presents an overview of the academic literature on philanthropy, divided in two parts: 1. Who gives how much; 2. Why people give. In part 1 it surveys the literature on characteristics of individuals and households that are related to giving. In part 2, it identifys eight mechanisms as the most important forces that drive giving: (1) awareness of need; (2) solicitation; (3) costs and benefits; (4) altruism; (5) reputation; (6) psychological benefits; (7) values; (8) efficacy. The article evaluates the progress in almost 500 studies reviewed and suggests directions for future research on philanthropy.