Adolescence is a period of social, physical, and neurobiological transitions that may leave individuals more vulnerable to the development of adjustment problems such as internalizing and externalizing symptomatology. Extant research demonstrates how self-regulation can predict adjustment outcomes in adolescence; however, it has yet to be examined how longitudinal growth in self-regulation may predict individual differences in symptomatology. That is, adolescents who develop self-regulatory capacities such as executive functioning (EF; including shifting, working memory, and inhibitory control) more slowly than their peers may be at increased risk for maladjustment. Data were collected from 167 adolescents and their primary caregiver over approximately three years. At each time point, adolescents completed three behavioral tasks that capture the underlying dimensions of EF, and both adolescents and their primary caregiver completed measures of adolescent symptomatology. Parallel process growth curve modeling was used to test the associations between initial levels and trajectories of both EF and adjustment. Results did not reveal any significant associations between initial levels of EF and adjustment or between growth in EF and growth in adjustment. Furthermore, there were no differential associations between the different EF dimensions. However, post-hoc analyses revealed that longitudinal increases in growth of EF predicted lower externalizing (but not internalizing) symptomatology at Time 3 (controlling for Time 1). Findings suggest that those with more rapid EF development may be better able to regulate behavioral and affective states and thus be less likely to develop externalizing symptoms, and that both early levels and growth in EF may be important predictors of adolescent outcomes.