This chapter proposes to systematically distinguish between the notion of ‘religious international non-governmental organizations (NGO) and the notion of ‘religiously affiliated NGOs’. It explores empirical observations dealing with different generations of NGO networks in the context of the United Nations. The chapter deals with the proposal to use the notion of ‘religious affiliation’ as an analytic category to better understand religious international NGOs (RINGO) in international relations. Philip Fountain presents an approach to RINGOs that challenges the very notion of religion as an analytic category by emphasizing the political agenda that forms the basis of this category. Committee of Religious NGO presents itself as a network of formal representatives of RINGOs that are characterized by their affiliation to specific segments of religious traditions. Among those NGOs, organizations that are described as ‘religious’, ‘faith-based’ or ‘spiritual’–either by the protagonists inside the organizations and/or by others from outside the organizations–are subject to particular discussions.