Despite surging interest in legal socialization, it is unclear how youth develop legal cynicism. The present study examined two socialization mechanisms for youth legal cynicism: perceptions of police treatment and maternal legal cynicism. Additionally, we assessed the degree to which an adolescent’s legal cynicism predicts reoffending. Youth and their mothers (338 dyads, total N = 676) were interviewed following their son’s first arrest. Path modeling tracked the associations between youths’ perceptions of police treatment, youths’ and mothers’ legal cynicism, and youth reoffending. Results suggest that youths’ legal cynicism derives from their own perceived treatment by police and not from mothers’ legal cynicism. Additionally, youth who perceived the police to have treated them more fairly reported less legal cynicism and in turn reoffended less. Findings advance our understanding of the etiology of legal cynicism and can inform best practices for police interactions with youth.