Youth in the juvenile justice system evince high rates of mental health symptoms, including anxiety and depression. How these symptom profiles change after first contact with the justice system and – importantly – how they are related to re-offending remains unclear. Here, we use latent growth curve modeling to characterize univariate and multivariate growth of anxiety, depression, and re-offending in 1216 male adolescents over 5 years following their first arrest. Overall, the group showed significant linear and quadratic growth in internalizing symptoms and offending behaviors over time such that levels decreased initially after first arrest followed by a small but significant upturn occurring a few years later. Crucially, multivariate growth models revealed strong positive relationships between the rates of growth in internalizing symptoms and offending behaviors such that improvements in mental health related to greater decreases in offending, and vice versa. These results highlight the reciprocal nature of internalizing and externalizing problems in adolescence, underscoring the importance of considering mental health alongside offending in the juvenile justice system.