The study used longitudinal family data from both the GENESiS and GENESiS1219 projects (Genetic Environmental-Nature of Emotional States in Siblings). The GENESiS study is a British-based study of subjects recruited through the Medical Research Council's General Practice Research Framework. The sample used for this study consisted of 808 male adolescents, 925 female adolescents, and 14 adolescents of unknown sex. A total of 1,294 parents participated in the study. Study instruments measured parental characteristics, family environment, and adolescent depression, with the dependent variable being severe adolescent depressive symptoms at time 2. The data were analyzed with a series of logistic regression analyses. The study found that the odds of severe adolescent depressive symptoms increased by a factor of 1.5 per standard deviation increase in parental familial vulnerability to depression (odds ratio=1.5). Parental body mass index and educational level had significant influences on adolescent depressive symptoms independent of parental vulnerability. Only parental education was a significant risk factor independent of the effects of parental familial vulnerability. An interaction between parental familial vulnerability and parental education level posed the highest risk for adolescent depressive symptoms. These results, if replicated, suggest that adolescents with a family history of depression whose parents also have low educational attainment are at especially high risk for severe depressive symptoms. 2 tables and 34 references