In this study, we examined trajectories of symptom reduction and family engagement during the modular treatment phase of a clinical trial for early-onset disruptive behavior disorders that was applied either in community settings or a clinic. Participants (N = 139) were 6–11 year-old children with diagnoses of Oppositional Defiant Disorder (ODD) or Conduct Disorder (CD). Symptoms of ODD/CD and level of engagement were assessed at every session during the course of treatment. Overall, symptom reduction was characterized by a gradual decline in symptoms over the first 11 sessions followed by a flatter slope beginning with session 12. Clinic participants evidenced a greater decline in symptoms after session 11 compared to participants in community settings. Overall, engagement remained stable during the course of treatment. However, clinic participants had higher levels of engagement throughout treatment compared to participants in the community settings. These setting differences in level of engagement did not account for the differences in trajectories of symptom reduction across the treatment settings.
