For six decades, scholars have relied on Erving Goffman’s (1961) theory of total institutions to understand prison culture. Viewing prisons as total institutions offers insights into role performance and coercive control. However, mounting evidence suggests that prisons are not, in fact, total institutions. In this article, I first trace two credible challenges to the idea of prison as a total institution based on existing data: that prison gates open daily and that prisons operate within a context of overlapping surveillance and (...) punishment supported by broader political and economic interests. Second, I draw on empirical findings from my own yearlong ethnographic study inside one U.S. state women’s prison to illuminate a third challenge to the total institution paradigm. Using religion in prison as a case study, I describe the process of institutional infusion, in which an outside institution proffers attitudes, practices, and resources that individuals may draw on to shape their material and interpretive experiences within a host institution. Prisons are structured to accommodate institutional infusion, further calling their totality into question. I conclude that we can learn far more about the realities and inequalities of the prison experience by viewing prisons as porous institutions. (shrink)