Toward the development of a new parent-rating for insomnia, this multi-site qualitative study explored sleep problems and related impacts in children with autism spectrum disorder (ASD) and their families. To ensure content validity of the measure, we conducted six focus groups with caregivers (N = 25) of 24 children (age 3 to 18 years) with ASD. Based on parent report, all children had a history of mild or greater insomnia. The focus group transcripts were systematically coded to identify major themes. Verbatim comments from caretakers were used to generate 134 candidate items. Further review by the research team and an expert panel followed by individual cognitive interviews with 12 parents reduced the item bank to 40. The thematic analysis of focus group transcripts identified 7 categories: (1) Trouble falling asleep; (2) trouble staying asleep; (3) early morning waking; (4) bedtime routines; (5) parental strategies for bedtime management; (6) impact of sleep problems on the child; and (7) impact of sleep problems on the family. The Flesch Kincaid Grade Level of the 40-item version was 7.2 (seventh grade reading level). Insomnia in children with ASD shares features in common with insomnia in the general pediatric population. However, perhaps owing to autistic features such as insistence on sameness, sensory sensitivities, communication impairments, insomnia in children with ASD appears to have unique behavioral manifestations. Content validity and item clarity of the 40-item bank were supported by expert panel review and cognitive interviews with caregivers of children with ASD.