Ethnic identity development can play a role in youths' perceptions and attitudes concerning police, but this process has not been explored in delinquent samples. In this article, we examine how youths' perceptions of police legitimacy and levels of legal cynicism are related to processes of ethnic identity development. Participants were 561 black youth ages 14-18 (12% female) who were adjudicated of a felony or serious misdemeanor. Data were taken from semi-annual interviews conducted over 3 years. Increased ethnic identity exploration was related to positive perceptions of police legitimacy and lower legal cynicism. Higher ethnic identity affirmation predicted higher perceived legitimacy over time, but affirmation was not related to legal cynicism after accounting for psychosocial maturity. This study provides evidence that ethnic identity development operates similarly among high risk youth as in non-delinquent samples, and that it is connected to beliefs that can have implications for juvenile offenders' future compliance with the law.