Against the backdrop of the ‘formatting of religions’ thesis, this paper presents the outcomes of empirical research on religious assistance in ten prisons in the Italian region of Lazio. We construct a typology of the forms of relationships that exist between prisons and religious organisations in an increasingly pluralist context. These relationships can have their bases in (1) misrecognition, which is strictly speaking a form of non-relation; (2) adaptation, with a distinction drawn between instrumental adaptation, on the one hand, and formatting, on the other; (3) conflict; or (4) cooperation and mutual transformation. Each form of relationship is explained and discussed through the experiences of relevant individuals, with stories drawn from interviews conducted during our research. This typology shows that, in the Italian case at least, a context of religious pluralism and the coexistence of religious and secular worldviews and practices in public institutions do not necessarily have a ‘formatting’ effect on religious organisations, nor lead to any form of mutual transformation or ‘complementary learning’ process taking place. This ‘complementary learning’ process has been taken in our research as a working hypothesis. We take the term from the broader theoretical debate about the postsecular, but we want to make the point that the postsecular also has an empirical dimension which can be described and assessed through the kind of sociological research we conduct in this paper. This paper explores why no such complementary learning process has developed between institutions and religious groups in the Italian context, and briefly highlights how, conversely, this kind of postsecular relationship is promoted in the UK. At the same time, it argues that forms of resistance from religious groups to institutional formatting pressures can be observed in both the British context and in the results of our own research.