Autism spectrum disorders (ASDs) represent a range of behavioural phenotypes defined by impaired development in social interaction, communication, imagination, and range of interests or behaviours. The aetiology and epidemiology of these serious developmental disabilities (DDs) are poorly understood. Estimates of the population prevalence of ASDs have varied widely within the US and abroad, with increasing estimates in most of the recent studies. In an effort to improve our understanding of the prevalence, population characteristics and public health impact of these conditions, the Centers for Disease Control and Prevention has funded a multi-site surveillance network for ASDs and other DDs that consists of programmes known as the Autism and Developmental Disabilities Monitoring (ADDM) network which conducts surveillance activities and the Centers for Autism and Developmental Disabilities Research and Epidemiology (CADDRE) which also conducts surveillance in addition to special research studies related to the ASDs. This collaboration will be referred to hereafter as the ADDM Network. The ADDM Network is implementing a multiple-source surveillance programme to determine population prevalence and characteristics of ASDs and other DDs. This paper describes the collaborative efforts and explains the methods in developing this coordinated public health surveillance network to provide an ongoing source of high-quality data on ASDs.