There is converging evidence that many people overestimate how frightened they will be when faced by a fear-provoking situation (Arntz & van den Hout, 1988, Behaviour Research and Therapy, 26, 207-223; Rachman & Bichard, 1988, Clinical Psychology Review, 8, 303-313; Rachman, 1990, Fear and courage (2nd edn). New York: W. H. Freeman). This overprediction of fear is commonly seen in people who are troubled by excessive fear (e.g. claustrophobics, panic patients), but is not confined to them. Anecdotal, clinical, and research evidence suggests that the tendency to overestimate the subjective impact of an aversive event is a common psychological phenomenon. This review will present examples of overpredictions, put forward some explanations of why people might overpredict, consider the function that overpredicting might serve, and the possible consequences of overpredicting. The process by which overpredictions are reduced is also considered and an attempt will be made to relate this strong tendency to overpredict fear to other types of psychological overestimation.