In this “Leadership Series” paper, Emmett Carson, CEO and president of Silicon Valley Community Foundation, provides a thoughtful examination of fundamental questions facing U.S. community foundations today. Acknowledging that a key characteristic of community foundations is their leadership and civic engagement within their stated geographies, Emmett explores how these institutions are engaging with donors who have a wide range of interests in diverse geographic areas. 21st-Century Community Foundations is intended to be a springboard for the ongoing conversation about the changing definition of community.