Policymakers, civic leaders, and scholars have increasingly focused their attention over the last decade-and-a-half on the importance of voluntary participation in civil society. From George H. W. Bush's Thousand Points of Light to Bill Clinton's AmeriCorps to George W. Bush's faith-based initiatives, it is undeniable that communities are looking to increase their levels of charity and voluntarism in the provision of public goods and services.What mobilizes giving and volunteering?...