<p><strong>Background and objectives:</strong> Recently, more attention has been placed on contributing factors for different prevalence rates of ASDs/PDDs in geographical areas. This study examines the association between diagnosis of ASDs and distance to regional intervention centres using a population-based dataset of children attending Senior Kindergarten classes in Ontario. Demographic and socioeconomic variables were also examined to find significant predictors for diagnosis of ASDs.</p> <p><strong>Methods:</strong> Data from all sites of Ontario with completed Early Development Instrument (EDI) in school years 2009/10 and 2010/11 were included. Individual-level variables were derived based on the data provided by EDI. Neighbourhood-level variables on socioeconomic factors of children’s place of residence were obtained through census data.</p> <p><strong>Results:</strong> 708 out of 66,284 children were reported by teachers to have diagnosis of ASDs, which results in a prevalence rate of 1.0% for ASDs. Children living near regional centres were less likely to be in the diagnosed group (OR=0.77). Moreover, children living in neighborhoods with high proportion of adults with high school diplomas and high proportion of single-parent families were more at risk of being reported as diagnosed (OR=1.27 & 0.73; respectively). MCYS region that a child lives in was found to be another significant predictor for teacher-reported diagnosis of ASDs.</p> <p><strong>Conclusion:</strong> Regional centres were not the only centres providing interventions to children with ASDs in Ontario. Therefore, having in-detailed information about the exact place of receiving intervention for each child would be beneficial. Furthermore, having single-parent family structure as a significant predictor necessitates specific policies for these families to obtain appropriate services, reduce caregiver’s stress, and improve family functioning.</p> / Thesis / Master of Science (MS)