Scholarship on U.S. litigation and civil procedure has scarcely studied the role of private enforcement in the states. Over the past two decades, scholars have established that, almost uniquely in the world, the U.S. often relies on private parties rather than administrative agencies to enforce important statutory provisions. Take your pick of any area in American governance, and you will find private rights of action: environmental law, civil rights, employment discrimination, antitrust, consumer protection, business competition, securities fraud, and so on. In each of these areas, Congress has deliberately empowered private plaintiffs instead of, or in addition to, government agencies. Yet, despite the vast importance of private enforcement at the federal level, we have no account of how prevalent private rights of action are in state law. And this question is particularly pressing now that a number of states— triggered by the Texas abortion law S.B. 8—are using private enforcement to weaken constitutional rights. Is private enforcement a meaningful method of governance in the states or just at the federal level? Which political conditions lead to the adoption of state private enforcement? And why does it exist? In this Article, we conduct the first systematic empirical investigation of the hidden world of state private enforcement. Using computational linguistics and machine learning, we identify private-enforcement provisions across a unique dataset of all fifty states’ laws going back to 2003. Our results show that private enforcement is ubiquitous at the state level. Even by conservative estimates, there are more than 3,500 private-rights-of-action provisions in state law, ranging from traditional areas like antitrust and employment all the way to privacy violations, lawsuits against police, gravedigging, veterinary care, and waste disposal. Counterintuitively, private-enforcement provisions are expanding the most in an ideologically mixed group of small states like Utah, New Hampshire, Connecticut, ...