NGO collaborations and government–NGO relations have become popular subjects of inquiry in public administration. Building on contemporary trends in the field, this exploratory study adopts a transnational governance perspective to examine the collaborative propensities of transnational NGOs registered in the United States. Unlike prior scholarship focusing on subnational samples of domestic organizations operating within single sectors of activity, findings are based on a mixed-method analysis of in-depth, face-to-face interviews with top organizational leaders from a diverse sample of 152 transnational NGOs spanning all major sectors of NGO activity. Analysis discovers that leaders’ organizations exhibit either an "independent" or an "interdependent" collaborative propensity. As members of global civil society, many transnational NGO leaders are reluctant, if not averse, in their attitudes toward collaboration with actors outside of civil society, particularly government agencies. Leaders of independent transnational NGOs evince concern over the implications of intersectoral collaboration for organizational legitimacy, whereas leaders of interdependent transnational NGOs appear to be attracted to the increased funding and recognition that intersectoral collaborations may provide. Further analysis of the perceived benefits and obstacles to collaboration reveals additional insights about the factors influencing leaders’ decisions to engage in or not to engage in intersectoral collaboration.