Warnings are one of the primary ways that administrative agencies enforce the law. Yet there is virtually no scholarship interrogating the role that warnings play in an agency’s arsenal. Are they effective in motivating compliance? If so, under what circumstances? Is reliance on warnings warranted at all? This Article tackles these important but overlooked questions. Economic models of public enforcement suggest that warnings have no role in motivating compliance. Published data on the effectiveness of warnings is virtually non-existent. Yet, in an apparent act of faith, administrative agencies rely heavily on warnings—often as their primary enforcement mechanism. This Article scrutinizes this use of warnings, through both a theoretical assessment and a case study of their efficacy in one particular context—the federal Animal Welfare Act (AWA). After showing that that warnings issued under the Animal Welfare Act appear to frequently fail to incentivize compliance, the Article then assesses why this might be and discusses the implications of this failing for the many administrative agencies that rely on warnings. It also makes policy recommendations for improving the efficacy of warnings, including recommendations about disclosure that are especially timely given recent moves by the federal government to delete thousands of enforcement-related records from its websites.