The numerous empirical and conceptual studies that have been conducted over recent years concerning the social responsibility of enterprises and their contributions towards sustainable development have given very little consideration to non-profit organizations (NPOs). This is surprising, because NPOs are confronted with very similar challenges to profit-orientated enterprises regarding their evolution into sustainable organizations. This paper is a preliminary conceptual study and explores the question of why the corporate social responsibility, or corporate sustainability, of NPOs has to date been both neglected by research establishments and also extensively ignored by the NPOs during their day-to-day practical management. The example of church and pastoral institutions in Germany is used to demonstrate the extent to which they take account of ecological and social aspects in their management systems and processes and, thus, implement sustainable management within their day-to-day practice. The paper concludes with some proposals for further empirical and conceptual research projects, which are designed to analyze developments within NPOs with relation to the integration of sustainability into their management systems and processes.