Surveys of autism spectrum disorders (ASDs) are important to estimate the proportion of children in a population who are suffering from this serious developmental handicap. The result of the surveys can help health and educational authorities to improve access to early detection diagnosis and intervention and generally to improve awareness about these conditions in various countries. Surveys of ASDs are now conducted in many countries worldwide and they have shown that at least one child in 150 suffers from one of these disorders. There has been thus far no survey of autism in Mexico and awareness and services in Mexico need to be improved. We are planning to conduct a full population survey of ASDs in the State of Guanajuato. This proposal is to develop a pilot study which will help to develop the Mexican version of instruments, to test data collection procedures in schools and within the health system, and to sensitize the population to the need to obtain an accurate picture of autism in Mexico. It is anticipated that at the end of this pilot study, the team - consisting of an expert clinical team from Mexico alongside an epidemiological research team of a Canadian university . will conduct the first population survey of ASDs in Mexico.