U.S.-based private and voluntary organizations (PVOs) play an important role in international assistance. To assess this role, we constructed a new data set that covers over 1600 secular and religious PVOs that registered with the U.S. federal government between 1939 and 2004. In the post-WWII period, major revenue patterns are the rise of Evangelical PVOs, decline of Jewish PVOs, and rapid growth of secular PVOs from the mid 1980s to mid 1990s. We analyze the determinants of changes in PVO size, gauged by real revenue. We focus on the interplay between public revenue (from the federal government, international organizations, and other governments) and private revenue. Specifically, we investigate whether funds from the federal government and other public entities serve as a magnet for subsequent private support.