How does religious change in society affect welfare organization practices and the religious aspects of the welfare state? Theories of historical institutionalism suggest that welfare organizations are highly stable, but this study finds that individual-level religious trends provoke corresponding welfare-organizational change. Three mechanisms link individual-level change to changes in organizational religiosity: workforce influence, welfare client demands, and political intervention. To demonstrate how these mechanisms connect social to organizational change, the study explores the effect of individual-level secularization in Belgium and the Netherlands on hospitals and welfare agencies. In contrast, a case from Israel evaluates the effect of individual-level sacralization on the same types of organizations. Organizational-level change takes the form of institutional conversion: religious providers discard most of their religious manifestations in a secularized environment but, conversely, public welfare providers adopt religion-conforming practices in an increasingly religious society.