Catholic led health and social care services have a long history and tradition in Ireland. Indeed, as noted by Wren (2003), the development and growth of voluntary hospitals throughout the nineteenth and twentieth centuries owes a great deal to the thousands of religious (primarily women) who worked for little financial reward, accepting the practice of putting their salaries back into the hospitals where they worked. In the latter part of the 20th century, due to a myriad of reasons including diminution of vocations and mandates from Vatican II, religious institutes began to explore how organisational identity might be sustained within Catholic led health and social care once they themselves have moved on. In this study, the literature on faith based organisations (FBOs), mainly from the United States, is explored as context, particularly in terms of cultural and societal differences (Pew Research Centre, 2014, 2018; Smith, 2002) and the various typologies of FBOs in terms of determining the spectrum of religious expression in these organisations (Jeavons, 1998; Smith & Soisin, 2001; Monsoma & Mounts, 2002; Sider & Unruh, 2004). The literature on organisational identity has been reviewed specifically in terms of the role of identity construction (Dhalla, 2007; Gioia et al., 2013; Humphries & Brown, 2002), organisational identity threats (Ravasi & Schultz, 2006), multiple identities (Pratt & Foreman, 2000) and what that means in terms of the central, distinctive and enduring characteristics (Albert & Whetten, 1985) of any future identity of the former Catholic religious led health and social care services in Ireland. A constructive interpretive stance underpins this study. The primary research has two parts: firstly a series of unstructured, in-depth interviews with senior Religious and their lay counterparts within the leading religious institutes currently providing health and social care services in Ireland, and secondly, a case study of one specific religious institute, combining unstructured in-depth interviews with a small number of relevant stakeholders, field notes and archival material. As initial interviews took place in 2011/12/13, a further series of interviews took place in 2019, both with individuals from the case-study organisation and from external religious institutes and their health and social care services, which has provided greater depth and richness to the study. This study makes three major contributions which include identification of factors that may determine the sustainability of OI in the context of a faith-based organisation in the future in the absence of the religious institutes. The second contribution relates to the context of this study. Very limited research has been carried out on the role of religious institutes of Ireland in terms of the provision of health and social care. The research in this study adds to the limited pool of knowledge on this organisational form. Finally, this study contributes to the research on multiple identities by showing how the framework developed by Pratt and Foreman (2000) could be used to categorise how sense-giving OIC processes were used to respond to the emergence of multiple identities.