Legal scholars have largely neglected private policing, and the neglect is increasingly indefensible. The private security industry already employs more guards, patrol personnel and detectives than the federal, state and local governments combined, and the disparity is growing; to a striking extent, private firms now perform many of the beat-patrol tasks once thought central to the mission of the public police. This article describes what is known and unknown about the private security industry, traces the industry’s history, assesses the challenges and opportunities it creates for judges and scholars, and provides an agenda for future research and doctrinal development. Private security firms furnish tangible evidence about what some people want but are not receiving from public law enforcement, and the legal regime governing private security — deconstitutionalized, defederalized, tort-based, and heavily reliant both on legislatures and on juries — offers important opportunities to test some of the most persistent proposals for reforming criminal procedure law. In addition, because maintaining order and controlling crime seem paradigmatic governmental functions, private policing presents a unique and underused vantage point for reexamining the public-private distinction and the state action doctrine. Finally, and perhaps most importantly, police privatization provides occasion for reconsidering the focus of constitutional law on negative obligations of government, and the focus of constitutional criminal procedure on fairness to individual criminal defendants; the dramatic spread of policing-for-hire should prompt us to rethink what it means to guarantee all citizens, regardless of wealth, the equal protection of the laws.