The suitability of Gray's (1975) three-factor arousal theory as a model of human performance under stress was investigated in a study of basketball free-throw shooting. Free-throw attempts, made by members of an NCAA Division I men's varsity team, were videotaped during one full season. On the basis of Gray's theory, we predicted that increased stress (assumed to be present in games as opposed to practices) would be associated with longer pre-shot preparations and a greater incidence of overthrow shots. The prediction was confirmed by the results. Moreover, we found that free-throws were more frequently overthrown when attempted during crucial rather than non-crucial game situations. Further tests of the utility of Gray's theory are suggested.