The relations among social information processing (SIP), cardiac activity, and antisocial behavior were investigated in adolescents over a 3-year period (from ages 16 to 18) in a community sample of 585 (48% female, 17% African American) participants. Antisocial behavior was assessed in all 3 years. Cardiac and SIP measures were collected between the first and second behavioral assessments. Cardiac measures assessed resting heart rate (RHR) and heart rate reactivity (HRR) as participants imagined themselves being victimized in hypothetical provocation situations portrayed via video vignettes. The findings were moderated by gender and supported a multiprocess model in which antisocial behavior is a function of trait-like low RHR (for male individuals only) and deviant SIP. In addition, deviant SIP mediated the effects of elevated HRR reactivity and elevated RHR on antisocial behavior (for male and female participants).