Crowdsourced regulation has been discussed to date by legal and social science scholars mainly in the context of legislation and rulemaking, without paying sufficient attention to non-legislative regulatory functions. This article provides a richer theory of crowdsourced regulation which extends to all regulatory functions, focusing on monitoring and enforcement. Regulatory agencies worldwide harness the power of the public using digital platforms to carry out monitoring and enforcement tasks in regulated markets and sectors. For example, agencies operate online complaint databases that invite the public to report mistreatment of consumers and environmental nuisances by regulated firms. Agencies also publish information concerning corporate misbehavior to publicly shame companies into compliance. Crowdsourcing regulatory monitoring and enforcement can help minimize some prominent ailments of the regulatory task, such as poor resources, diminishing deterrence, declining legitimacy, and capture. It can also promote goals and values such as public participation, increased transparency, public trust in regulators, administrative efficiency, and effectiveness in achieving regulatory objectives. However, crowdsourcing regulatory monitoring and enforcement is subject to a new set of legal, administrative, and democratic failures that need to be acknowledged and addressed. The article develops a theory of crowdsourced regulation that supplies justifications and rationales for crowdsourced regulatory monitoring and enforcement, points out its main pitfalls, and normatively evaluates law and policy implications.