||The religious sphere in Spain is changing substantially, becoming simultaneously more diverse and more secular. However, empirical research on the processes of adaptation and response of public institutions to the new religious environment is still very scarce. This paper analyses the ways in which public institutions respond to transformations in the religious sphere, and how the Catholic legacy is negotiated within such contexts. By combining a legal and policy perspective with an ethnographic approach to everyday practices within hospitals and prisons in two Spanish regions, we shed light on the institution-specific and the contextual factors that condition the de-confessionalization and the accommodation of religious diversity in Spanish institutions. The findings show some internal incoherence in the implementation of legal-political measures and in the attitude of the Catholic Church.