Only circumscribed aspects of highway aggression have been investigated. The upsurge of abuse and violence transpiring between motorists necessitated a more definitive depiction of the actual events, participants, and relevant contextual features. A questionnaire administered to 120 motorists, aged 18 to 68, solicited a recountal of incidents occurring within 12 months and a description of their most recent encounter. Based on severity of experience, subjects were relegated to distal threat, direct threat, and nonvictim groups. Although most events involved unreported distal threats lasting less than three minutes, men and non-college graduates were more often directly threatened, while non-victims were predominantly women and college graduates. Perpetrators were primarily unknown Caucasian males who generally aggressed in populated areas during afternoon hours.