Agency accreditation has grown steadily as a management strategy in recent decades. Accreditation is meant to help professionalize public administration work by requiring an agency to adopt policies and practices that are sanctioned by an external organization. Advocates claim that accreditation facilitates the diffusion of best practices and builds a culture of professionalism in an agency. Accreditation clearly leads agencies to adopt formal policies. This article identifies two ways in which accreditation might affect organizational culture: (1) by socializing employees, and (2) by signaling the agency’s priorities to employees. Analyzing attitudinal data from officers in six American police departments, this study finds no association between accreditation and officers’ own values, but finds that accreditation is strongly correlated with officers’ perceptions of their agencies’ priorities.