Objective: Identifying risk factors for adolescent depression is an important research aim. Overgeneral autobiographical memory (OGM) is a feature of adolescent depression and a candidate cognitive risk factor for future depression. However, no study has ascertained whether OGM predicts the onset of adolescent depressive disorder. OGM was investigated as a predictor of depressive disorder and symptoms in a longitudinal study of high-risk adolescents. In addition, cross-sectional associations between OGM and current depression and OGM differences between depressed adolescents with different clinical outcomes were examined over time. Method: A 1-year longitudinal study of adolescents at familial risk for depression (n = 277, 10-18 years old) was conducted. Autobiographical memory was assessed at baseline. Clinical interviews assessed diagnostic status at baseline and follow-up. Results: Currently depressed adolescents showed an OGM bias compared with adolescents with no disorder and those with anxiety or externalizing disorders. OGM to negative cues predicted the onset of depressive disorder and depressive symptoms at follow-up in adolescents free from depressive disorder at baseline. This effect was independent of the contribution of age, IQ, and baseline depressive symptoms. OGM did not predict onset of anxiety or externalizing disorders. Adolescents with depressive disorder at both assessments were not more overgeneral than adolescents who recovered from depressive disorder over the follow-up period. Conclusions: OGM to negative cues predicted the onset of depressive disorder (but not other disorders) and depressive symptoms over time in adolescents at familial risk for depression. Results are consistent with OGM as a risk factor for depression. (Contains 1 figure and 3 tables.)