Little is known about autism spectrum disorders (ASD) in most low income countries, especially in underserved South Asia, where access to health professionals to diagnose and treat child development disorders, like autism, are virtually non-existent. This study describes an attempt to screen, diagnose, and estimate the prevalence of ASD among ~11,000 children 7-9 years of age within 600 villages located in a rural area in northwest Bangladesh. This study will be conducted as a two-phase screening and diagnostic survey, carried out by well-trained staff, using accurately translated forms, following highly standardized methods guided by a joint Johns Hopkins-Bangladeshi scientific team. In addition, the health, dietary and socioeconomic histories of the children under study are known, via assessments of the mothers in pregnancy, and the children themselves in infancy. This was done as part of two earlier field trials between 2001 and 2007 that evaluated the health and survival rates of children following maternal vitamin A and beta-carotene supplementation during pregnancy and administration of a large dose of vitamin A to the baby at birth. Thus, the results of this study will include the first estimates of the prevalence of autism in South Asia by using globally recognized methods as well as data collected during fetal life, at birth and in early infancy. This study has the potential to impact our understanding of why some children develop, and others do not develop, this developmental disorder.