Objective: The purpose of this study was to estimate associations between cumulative exposure to adverse childhood experiences (ACEs), protective factors, and co-occurrence among male and female juvenile offenders. Study design: Cross-sectional study. Methods: Validated measures of ACEs, internal resilience, external youth assets, psychological distress, and substance abuse were collected from 429 youths involved in the juvenile justice system in Nevada. A three-level outcome variable was created using the psychological distress and substance use measures: no problems, one problem, or co-occurring problems. Hierarchical multinomial logistic regression models were used to determine the independent, direct, and moderating impact of the protective factors on ACEs and the outcome. Results: Internal resilience, family communication, school connectedness, peer role models, and non-parental adult role models were associated with lower odds of co-occurrence compared to having no problems (adjusted odds ratios [AORs] ranged from 0.11 to 0.33). When ACEs were added to the model, internal resilience and all assets except for one (non-parental adult role models) continued to offer protection against co-occurrence. Internal resilience was the only protective factor that significantly moderated the association between ACEs and co-occurrence (AOR, 0.24; 95% CI, 0.06, 0.99). Conclusion: Most protective factors decreased co-occurring mental health and substance abuse problems in the presence of ACE exposure and internal resilience moderated the relationship between ACEs and co-occurrence. Juvenile justice systems should use positive youth development approaches to help prevent co-occurrence among youths. (C) 2021 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.