Exposure to ozone is a well-documented risk factor for negative physical health outcomes but has been considered less frequently in the context of socioemotional health. We examined whether levels of neighborhood ozone predicted trajectories of depressive symptoms over a four-year period in 213 adolescents (ages 9-13 years at baseline; 57% female; 53% of minority race/ethnicity). Participants self-reported depressive and other types of psychopathology symptoms up to 3 times, and their home addresses were used to compute ozone levels in their census tract. Possible confounding variables, including personal, family, and neighborhood characteristics, were also assessed. We found that higher ozone predicted steeper increases in depressive symptoms across adolescent development, a pattern that was not observed for other forms of psychopathology symptoms. These findings underscore the importance of considering ozone exposure in understanding trajectories of depressive symptoms across adolescence.