In 2001, the Autism Spectrum Disorders–Canadian-American Research Consortium ( ASD - CARC ) launched a program of research on autism spectrum disorders ( ASD ). As part of that undertaking, and in response to concerns about the growing proportion of children diagnosed with ASD , ^{1 , 2} the National Epidemiologic Database for the Study of Autism in Canada ( NEDSAC ; www.nedsac.ca ) was created as a multi-site ASD surveillance program. Government departments, clinicians and researchers [*] collaborated to establish regional teams to collect information (see Table 1) on children with ASD in British Columbia, Calgary (Alberta), Manitoba, southeastern Ontario, [†] Prince Edward Island, and Newfoundland and Labrador. NEDSAC provides estimates of the prevalence of ASD in Canadian children and a profile of those who are affected, ³ and allows researchers to monitor trends in age at diagnosis. ⁴ These data can help the health, education and social services sectors with planning and allocation of resources. ^{5 , 6}