The objective of the conference on “Leadership, Altruism, and Social Organization” was to bring researchers together who were interested in exploring the functioning of the nonprofit sector. The conference and this special issue focus on three themes. First, what causes social and volunteer-based organizations to successfully compete against a private enterprise? Second, why do individuals or organizations take the lead in providing or securing provision of public goods? Third, what are the consequences of having altruistically motivated agents, and how can such motives be sustained?