Because businesses regularly sell alcoholic beverages to underage individuals, law enforcement agencies must give priority to compliance checks of establishments that serve and sell alcoholic beverages. This is a cost-effective use of law enforcement resources, since the enforcement of underage drinking laws can help prevent traffic crashes, the major cause of death among youth; can lower the frequency of social problems among youth; and can help prevent aggressive behavior by youth, such as assaults and rape. Once organized, compliance-check operations are easy, quick, and inexpensive. The chronology of two compliance-check projects are presented to show how they produced a significant reduction in illegal alcohol sales to youth. In presenting a step-by-step approach for developing and conducting compliance checks, this manual first outlines pre-operation activities, with attention to determining the type of compliance check, ordinance review/revision, identifying decisions to be made, site selection, plan review, prior notice to the community and businesses, hiring and training buyers, and logistics. Guidelines are then presented for implementing and conducting compliance checks, including post-operation activities. 4 references and 20 appendixes with sample materials, checklists, and model ordinances