Chiefs of the 500 largest police departments in the United States were contacted by mail. They were asked to provide information on the characteristics of police personnel, both sworn and nonsworn, whose past behavior indicated they were either resistant or prone to divulging restricted information to unauthorized individuals. Data were obtained in 51 cases, 37 violators and 14 refusers. The typical violator was a white, mid-career employee who supplied fairly innocuous information to someone he or she knew fairly well. More serious cases tended to involve employees who were not getting along well with others (superiors, coworkers, or spouses), felt that they were not being treated fairly by the police department, and had lost interest in their work. A five-step conceptual framework of factors involved in espionage is described. Recommendations to curtail the release of restricted information are offered that focus on clarifying what constitutes restricted information, appropriate sanctions, the need for open communication channels between police employees and management, information control systems, and the use of psychological testing and background investigations to screen out employees who may not be loyal. 17 references and 2 tables