Despite these limitations, our findings document the high prevalence of mental disorders in youth, and specify that just over one in four-to-five adolescents in the general population suffers from disorders that result in severe impairment. Considered with recent estimates indicating that the annual economic burden of mental disorders on the well-being of American youth and their families approaches a quarter of one trillion dollars45, these findings underscore the key public health importance of mental health in American youth. The present data can inform and guide the development of priorities for future research and health policy by providing previously lacking prevalence estimates in a nationally representative sample of U.S. adolescents, as well as the individual, familial and environmental correlates of mental disorders. Prospective research is now needed to understand the risk factors for mental disorder onset in adolescence, as well as the predictors of the continuity of these disorders into adulthood.