Without slighting the important role played by controlled psychological processes in human aggression, this paper recommends that considerable systematic attention should also be given to the operation of automatic processes in bringing about this behavior. The concepts of automaticity and impulsivity are discussed briefly and it is proposed that many impulsive actions, particularly antisocial ones, are due to failures of restraint after they were initiated involuntarily. A number of experiments are reviewed in which situational stimuli automatically instigated or heightened aggressive inclinations. These have to do with associations in hostility displacement, reactions to stigmatized persons, and association in aggressive reactions to media violence. The last-mentioned studies deal especially with factors affecting the selection of the target for aggression. In discussing these findings it is suggested that after the crucial situational features had automatically initiated the sequence of determinants, the aggression displayed could have been due either to a hostile appraisal of the target or the activation of aggression-related bodily reactions as well as hostile ideas. It is also hypothesized that in at least one of the studies, an experienced negative affect might have instigated the aggression independently of any appraisals.