This chapter charts the most recent history of the private criminal justice system, from its lowest point of influence in the 1960s to modern times, when private police outnumber their public counterparts by almost a two-to-one margin. It also notes that private police are distinctive not just because of their sheer number but because of the goals that they seek to achieve – which are essentially the goals of the client who is paying them or the goals of the neighborhood or volunteer associaton that they represent. The chapter examines not only paid private police but also volunteer private police, such as the Guardian Angels, the Chicago Alternative Policing Strategy, neighborhood watch programs, and “white hat” hackers.The chapter concludes by pointing out the relatively low level of regulation that applies to private police and by examining the pros and cons of using private police to detect and apprehend criminals.