OBJECTIVES: Since 2011, 3 outbreaks of botulism in US prisons have been attributed to pruno, which is an alcoholic beverage made by inmates. Following 1 outbreak, we conducted a qualitative inquiry to understand pruno brewing and its social context to inform outbreak prevention measures. METHODS: We interviewed staff, inmates, and parolees from 1 prison about pruno production methods, the social aspects of pruno, and strategies for communicating the association between botulism and pruno. RESULTS: Twenty-seven inmates and parolees and 13 staff completed interviews. Pruno is fermented from water, fruit, sugar, and miscellaneous ingredients. Knowledge of pruno making was widespread among inmates; staff were familiar with only the most common ingredients and supplies inmates described. Staff and inmates described inconsistent consequences for pruno possession and suggested using graphic health messages from organizations external to the prison to communicate the risk of botulism from pruno. CONCLUSIONS: Pruno making was frequent in this prison. Improved staff recognition of pruno ingredients and supplies might improve detection of brewing activities in this and other prisons. Consistent consequences and clear messages about the association between pruno and botulism might prevent outbreaks.