Although both depression and substance use have been found to contribute to suicide attempts, the synergistic impact of these disorders has not been fully explored. Additionally, the impact of subthreshold presentations of these disorders has not been researched. We utilized the Quadrant Model of Classification (a matrix of severity of two disorders) to assess for suicide attempt risk among adolescents. Logistic regression was used to examine the impact of co-occurring disorder classification on suicide risk attempts. Results indicate that quadrant classification had a dramatic impact on suicide attempt risk, with individuals with high severity co-occurring disorders at greatest risk. (Contains 1 table and 2 figures.)