This small volume is packed with significant and interesting results of a large-scale national epidemiologic survey of mental disorders in 12 regions in China. Sponsored by the Bureau of Medicine of the Ministry of Health in the People's Republic of China, with assistance from the World Health Organization, 12 centers in China were surveyed by 12 collaborating teams. Each of the centers included different geographical and sociocultural environments, and each center had a rural and urban sample of 500 households. The total sample consisted of 12,000 households comprising 51,982 individuals, 38,136 of whom were older than 15 years of age, drawn from a total sampling frame population of 2,313,470. The survey used a three-part design comprising a psychosis (key informant) survey, a children's survey, and a neurosis sampling survey. All the field work was carried out between July 1 and September or October 1982; the reference day for the point prevalence was July 1, 1982.