Material and Method: Three hundred three parents of children with ASD were recruited from the local autistic centers and schools in Bangkok, Thailand. A set of demographic information sheet, the Childhood Autism Rating Scale (CARS), the Life Oriented Test-Revised (LOT-R), and the WHOQOL-BREF test were submitted for collecting parental information.

Results: Using Pearson Correlation, a significant negative association was found between child’s severity and parental quality-of-life while optimism was found to correlate positively with parental outcomes. The finding from path-analysis confirmed that impairment of language and repetitive behavior of an ASD child associated with optimism that, in turn, predicted level of parental quality-of-life in all domains.

Conclusion: The current findings assured a role of optimism as mediator between child’s severity and parental quality-oflife. Implications for the development of intervention focused on enhancing parent’s optimism were recommended.

Keywords: Autism spectrum disorder (ASD), Optimism, Quality-of-life, Mediating role