This article surveys the state of emerging geographic research on detention, imprisonment, and confinement. Prisons and detention centers vary widely in location and form, but all hold human beings without consent by other human beings. We first survey geographical research on prisons and, second, on detention centers. We then argue that this geographic research offers three primary contributions to the study of imprisonment and detention. First, analyzing the spatial practices (the ordering of space and time) of these institutions provides a productive framework for understanding the materiality of social, cultural, and economic relationships. Second, this research provides an important perspective on state responses to the globalization of trade, migration, war, and security. Third, detention and imprisonment are productive sites for exclusionary discourses. In closing, we urge geographers to think deeply about how detention's indeterminacy works beyond the detention center, to be wary of implicit valorizations of imprisonment, and to take seriously the global expansion of the confinement industry.