Who benefits (cui bono) from an ostensibly public organization’s structures and practices? I draw on interviews, observation, and archival data from 25 independent foundations to examine the mechanisms by which "charitable" institutions are designed to serve the private interests of internal members. I develop a framework to analyze how both private and public goals inform organizational design, exploring the dual, continuous, and dynamic nature of this process. This framework enables scholarship on nonprofit organizational behavior to examine private interests in a uniquely robust manner. Furthermore, it provides tools to study organizations’ evolution through varied functions and forms over time.