This essay provides a brief overview of what is known about what causes prison violence, and how it can be prevented or reduced. The focus is interpersonal violence rather than collective disorder or self-inflicted harm, but the review does encompass violence involving staff (whether as victim or perpetrator) as well as prisoner-to-prisoner violence. The method is a selective and interpretive review of the literature, drawing particularly on key theoretical models and well-designed empirical studies, rather than being a more formal systematic review or meta-analysis. The chapter includes an update of material in an earlier comprehensive review of the literature on violence and violence prevention (Chapter 5 in Homel, 1999).