This dissertation project is a multi-sited ethnographic analysis of the interplay of Catholic social ethics and healthcare provision at the fourth largest non-profit hospital system in the US. This 48-facility corporation is the flagship of Catholic healthcare but serves diverse California constituencies. The religious mission requires that the hospitals provide a preferential option for the poor and their services are intended to serve vulnerable populations. This project investigates the role of Catholic religious values in the design of healthcare policy and service delivery by administrators and other decision-makers. It explores situations of conflicting ethics and value systems between the religious system. It seeks to understand how these values are articulated and how priorities are negotiated between institutions and how policy is developed is developed to prioritize services and increase access for underserved and other vulnerable populations and balance the tensions of resource allocation, charity and cost-effectiveness. Ethnographic research methods in this 15 month project include: 1) daily participant observation in meetings and hospital practice, 2) modified life history interviews with 10-15 informants involved in ethics issues and policy design, 3) review and analysis of documents produced by the hospital system since 1997. Field sites reflect an explicit effort to work in federally recognized disproportionate share hospitals (DSH) and other facilities where services to vulnerable populations complicate operations policy and finance strategies in a changing healthcare marketplace. In a era of federal devolution of health and welfare services, this dissertation will provide insight into this policy implementation. Research results will speak to the issues of not-for-profit health and medical care, particularly to the broader social concerns underlying the concept of hospital "community benefit" activities, beyond the dollar figures of "uncompensated care" and "charity care." It is intended to provide information of interest to provider institutions, public and private policy makers concerned about the provision of health care services to low-income and other underserved and vulnerable populations. It will also inform the work of consumer groups and community partners working with faith-based organizations in health and social welfare.