Background: Time use studies uncover the organization of daily routine of families of children with disabilities. The objective of this study is to identify determinants of time spent caring for children/adolescents with cerebral palsy (CP), autism spectrum disorder (ASD), and typical development (TD). Methods: Participants were caregivers of children/adolescents with/without disability. Structural equation modeling tested a proposed model of time spent in child care. The variables in the model were as follows: questionnaire (families' socioeconomic status [SES]), children's functioning (The Pediatric Evaluation of Disability Inventory–Computer Adaptive Test [PEDI-CAT]); hours of care (daily diaries), number of adaptations used, and help with child care (parents' report). Distinct variable combinations explained 78% of the variation in the time to care (TD model), followed by 42% (ASD) and 29% (CP). Results: Adaptations indirectly affected time to care through its effect on functioning (CP); family's SES affected functioning through its effect on adaptation use (ASD). Conclusion: In conclusion, knowledge of factors affecting caregivers' time spent on children's care help occupational therapists implement family-centered strategies.