--- - |2+ Background Female involvement in the juvenile justice system (JJS) has increased rapidly in recent years. Although deficits in self‐control and responsibility are associated with delinquency and higher rates of police contacts and arrests, much of this research has focused on males and/or selected samples of youth who already have a history of JJS involvement. Furthermore, little is known about the extent to which police contacts and arrests may disrupt normative psychosocial maturation. Methods Police contacts, arrests, levels of self‐control and personal responsibility were assessed annually between 12 and 17 years in a population‐based sample of 2,450 adolescent females. Fixed‐effects regression models, which control for stable individual characteristics, were used to examine whether within‐adolescent changes in self‐control, and responsibility were associated concurrently and prospectively with police contacts and arrests, and vice versa. Results Across adolescence, 5%–12% participants reported police contacts and 1%–4% were arrested. After adjusting for covariates, within‐person increases in self‐control and responsibility were associated concurrently with decreased odds of police contact. Increasing responsibility also predicted lower likelihood of police contact in the following year. When testing reverse causation, results showed that police contact predicted next year decreases in personal responsibility, and that being arrested predicted decreasing levels of self‐control and responsibility in the following year. Conclusions The study shows more clearly than previous work that increasing levels of responsibility precede decreased police contact in nonselected adolescent females, and that contacts with the justice system during adolescence may delay or undermine normative psychosocial maturation, highlighting important targets for intervention. - Journal of Child Psychology and Psychiatry, EarlyView.