The WHO Global Burden of Disease Study estimates that mental and addictive disorders are among the most burdensome in the world and that their burden will increase over the next decades. However, these estimates and projections are based largely on literature reviews rather than on cross-national epidemiologic surveys. In order to move forward with public health initiatives aimed at addressing the global burden of mental disorders we need to carry out rigorously implemented general population surveys that estimate the prevalences of mental disorders, evaluate risk factors for purposes of targeting interventions, study patterns of and barriers to service use, and validate estimates of disease burden world-wide.