The incidence of positive reactors to tuberculin among the children and young adults is the best criterion of the tuberculosis problem in any community. It is far superior to mortality rates, since many persons who have tuberculosis die of other causes and the death certificates do not record the coexisting tuberculosis. One has only to consult postmortem records to obtain abundant evidence of this fact. Moreover, the morbidity rate does not approach the accuracy of the tuberculin test as a criterion of the tuberculosis problem, since, in approximately 80 per cent of patients, symptoms are a late manifestation and do not bring patients to physicians for diagnosis until the disease is well advanced. Indeed, there is an average period of approximately two and one-half years before symptoms appear during which the disease can be located by modern methods. In most cases there is a much longer period after the tuberculin