All 89 responding agencies conducted undercover investigations, mostly related to drug law offenses, vice crimes, stolen property, and organized crime. Sixty-four departments reported they had guidelines governing these investigations. These guidelines were predominantly procedural or authorizational. Procedural guidelines covered topics including recruitment of undercover officers, chain of command, equipment to be issued, reports, safety precautions, and auditing procedures. Authorizational guidelines described when and when not to conduct undercover investigations. They specified what types of investigations were authorized, what activities were restricted, and what controls were in place to ensure compliance. The guidelines in 34 responding agencies emphasized procedure over authorization, while 21 had authorizational guidelines exclusively or in combination with procedural guidelines; survey responses were incomplete for the remaining nine departments that had guidelines in place. 2 tables and 17 references