Prior research on law enforcement and court system actions suggests that offender demeanor influences practitioner decision making. However, few studies have examined a key implication of this body of work—namely, criminogenic factors associated not only with offending but also with demeanor may result in a greater likelihood of contact with and formal processing by law enforcement and the courts. Using data from the National Longitudinal Study of Adolescent Health, we test the hypothesis that low self-control, which is associated with a range of characteristics that might influence practitioner perceptions of individual offenders' demeanors, will predict greater contact and formal processing. Briefly, we found that low self-control was consistently related to criminal justice system involvement as measured by police contacts, arrests, age at first police contact, and arrest onset. The implications of the findings for theory and research are discussed.