Burglars were found to use three categories of environmental cues to assess risk factors: cues that indicate the surveillability of the proposed target site, cues that indicate whether or not the target site is occupied, and cues that indicate the degree of difficulty that might be expected in actually breaking into the site. The study revealed that burglars are opportunistic and are easily deterred or displaced from one target site to another. Situational factors such as the presence of a dog, alarm system, security hardware, and alert neighbors may be the most effective deterrents. When one or more of these risk cues are discerned by the burglar, the target is usually considered too risky and the burglary is aborted or displaced. This is especially true for the opportunistic burglar and less so for the non-drug-using "professional." These findings have particular relevance for burglary prevention, since they suggest that burglary is more easily prevented by situational measures than previously thought. 1 figure and 15 references