The author contends that perceptual deterrence is flawed in three respects. First, it is not time-specific enough and not capable of grasping the short-term impact of variations in sanctions. Second, it does not specify concrete contingencies in which crimes are committed. Third, it does not measure the emotional component of deterrence. Situational deterrence is simply the intimidating effect of dangers involved in a specific crime situation. Some offenders clearly experience fear when they commit criminal acts, and this fear may curtail some criminal activities. There is a limit, however, to the effect of fear; many offenders succeed in mustering their courage and engage in criminal acts despite the danger. In addition, some offenders enjoy the excitement generated by fear. Situational risks represent an important component of crime prevention, not only because they are taken into account by offenders in their cost-benefit calculations but also because they can trigger uncontrollable fear and sometimes thwart criminal acts. Such risks are associated with victim reaction, nature of the crime, and situational crime prevention. 49 references and 1 figure