The occupational cultures in which one is immersed have a profound impact on individual and group occupational identities (Ashforth and Kreiner, 1999). Occupational cultures are socially constructed patterns of shared thinking, feeling, and behaving, distinctly associated with particular occupations (Manning, 2007; Schein, 2010). The occupational cultures of prison officers provide a lens through which they perceive their challenging and complex working world, and their place in it. This paper provides insight into the nature of occupational cultures in Irish prisons and their interplay with the identities of prison officers, including their attitudes, feelings, habits, and practices. It identifies how these occupational cultures are challenged, perpetuated, and/or reinforced in our prisons. The paper presents some of the key findings from a large-scale study, commencing with the relationship between officers’ experiences of solidarity and conformity with high levels of entitativity.1 This will be applied to account for the conceptualisation of ‘jailing’, discretion, professionalism and legitimacy in prison officers’ occupational cultures. The paper draws on unprecedented access to conduct ethnographic research in four Irish prisons from 2015 to 2017, including 76 interviews with all ranks from prison officer to governor. It is complemented by data from a survey distributed to every prison in the state (n = 544). The analysis of prison officers’ occupational cultures and identities provides an in-depth understanding of the experience of prison work and the perception and appropriation of penal policy, while generating possibilities for future research, training, and policy.