RecruitingBehavioural interventionMechanisms of Rumination Change in Adolescent DepressionThis study will evaluate whether a newer treatment, rumination-focused cognitive behavioral treatment, which includes mindfulness and can be used to reduce ruminative habits, change ways in which key brain regions interact with each other (e.g.., often called connectivity), and whether these changes in habits and brain connectivity can reduce the risk for recurrence of depression in the next two years.