OBJECTIVE: Religiosity has been repeatedly proposed as protective in the development of depression, sociopathy and addictions. ADHD frequently co-occurs with these same conditions. Although ADHD symptoms may affect religious practice, religiosity in ADHD remains unexplored. METHOD: Analyses examined data from >8000 subjects aged 12 to 34 in four waves of the Add Health Study. Relationships of religious variables with childhood ADHD symptoms were statistically evaluated. Observed correlations of ADHD symptoms to depression, delinquency, and substance use were tested for mediation and moderation by religiosity. RESULTS: ADHD symptoms correlated with lower levels of all religious variables at nearly all waves. In some analyses at Wave IV, prayer and attendance interacted with ADHD to predict worsened psychopathology. CONCLUSION: ADHD symptoms predicted lower engagement in religious life. In adulthood, some aspects of religiosity interacted with ADHD symptoms to predict worse outcomes. Further research should explore whether lower religiosity partially explains prevalent comorbidities in ADHD.