Private security personnel play an important but largely overlooked role in the operation of CCTV surveillance to prevent crime in public and private areas. This role can take a number of forms, including active monitoring of cameras. Drawing upon a global database of CCTV evaluations (N=165), this article examines the function and performance of private security personnel as related to the effectiveness of CCTV. Findings indicate that CCTV schemes operated by private security personnel generated larger crime prevention effects than those operated by police or those using a mix of police and security personnel. Policy and research implications are discussed.