Observations of 283 aggressive acts by 86 individuals indicate that the experiences of aggressors, victims, and witnesses contribute to a spiral of aggression. Aggressors could be categorized as one-time or multiple aggressors, with the latter being responsible for the majority of violent acts, usually against persons. Multiple aggressors, relative to one-time aggressors, were more often involved in minor violence such as shoving and pushing, were more likely to engage in sexual harassment, exhibited an attitude of bravado, were more likely to be drinking, and were more often engaged in acts with other multiple aggressors. Individuals who were victims and witnesses on multiple occasions accounted for about a third of all victims and witnesses but accounted for 70 percent of all witness and victim experiences. Witnesses rarely if ever reacted to aggressors. Victims also did not usually react to an aggressor: They did so on only 38 percent of occasions. The most common victim reactions were flight and retaliation. Those with multiple victimizations were more likely to react to aggressors than were one-time victims. About 28 percent of all victims and witnesses were also aggressors, while 56 percent of aggressors also were victims and witnesses. Victims who also were aggressors were more likely to react to aggression by retaliation than by flight. 27 tables and 19 references.