Adolescent delinquency and identity formation have both been described in relation to the confusion, doubt, and need for individuation and autonomy faced by adolescents. While theoretical conceptualizations (e.g., Erikson, 1968; Moffitt, 1993) suggest that delinquency and identity formation might be developmentally intertwined across adolescence, this link had yet to be longitudinally examined. This study tested whether delinquency and identity are related and whether we could determine a developmental order considering both between- and within-person associations across adolescence. We examined these associations in a multi-informant sample of 497 Dutch adolescents followed for 5 annual waves from age 14-18. Between-person cross-lagged models showed that adolescents who scored higher on delinquency relative to their peers, scored lower on commitment and higher on reconsideration, 1 year later. Within-person cross-lagged models showed that when adolescents reported above their own average on delinquency, they reported decreased commitment and increased reconsideration 1 year later. Additionally, within-persons, when adolescents reported an increase in in-depth exploration compared with their own average they reported decreased delinquency 1 year later. From these results we can conclude that delinquency and personal identity are indeed related across adolescence. Experimenting with delinquency hampers identity formation by increasing reconsideration and decreasing commitment. Within-person results suggest that interventions tailored to increase in-depth exploration in adolescents may help to prevent adolescent delinquency.