Despite the advances on the assessment of quality of life, this concept is barely studied and is riddled with important limitations for those with autism spectrum disorder (ASD). This article is aimed at validating a questionnaire to assess quality of life of children with ASD and intellectual disability (ID). Based on the KidsLife Scale, geared toward people with ID, the most reliable items for those with ASD were selected. Study participants were 420 persons, from 4 to 21 years old. Results indicated that the KidsLife-ASD Scale measured eight intercorrelated domains, had good reliability, and exhibited adequate evidences of validity. KidsLife-ASD emerges as a helpful tool to guide person-centered planning addressed at improving quality of life.