This phenomenon, which can bring considerable added value to situational crime prevention measures, has been described as the complete reverse of displacement. Two processes associated with benefits diffusion are identified: (1) offender uncertainty about the extent of increased risk; and (2) exaggerated offender perception that rewards of particular crimes are no longer commensurate with the effort. These processes are labeled deterrence and discouragement, respectively. Recent research is reviewed that provides examples of both kinds of benefits diffusion. Ways of enhancing diffusion are explored, and a program of research is advocated to investigate offender perceptions of the opening and closing of criminal opportunities. The authors conclude that, just as situational crime prevention measures may have unintended costs in terms of displacement, they may also have equal unexpected benefits in terms of diffusion. 38 references, 3 notes, and 1 figure