One in 36 children in the United States have a diagnosis of autism spectrum disorder (ASD). Children with ASD have complex developmental, emotional, behavioral, and physical health needs due to differences in social interaction, patterns of repetitive behavior, and frequent co-occurring conditions (e.g., feeding difficulties, sleep disturbances). Family management is the response of a family and its members to chronic conditions. Research is needed to identify modifiable factors that can strengthen the family’s approach to caring for their child’s health. For this dissertation, a systematic review of the literature on feeding difficulties in ASD and a convergent (QUAN +qual) mixed methods study on family management of two neurodevelopmental conditions (ASD and Down Syndrome (DS)) were conducted. The quantitative arm enrolled 56 caregivers of children with ASD and 29 caregivers of children with DS who completed validated self-report instruments. The qualitative arm and integrated analysis included a nested sample of 30 caregivers of children with ASD who participated in semi-structured virtual interviews about managing daily caregiving challenges, specifically at mealtime and bedtime. The systematic review of the literature identified that feeding difficulties are associated with core features of ASD, persist with advancing age, and are a source of stress for families. In the quantitative arm of the mixed methods study, there were no significant differences in family management between groups. Across diagnoses, greater concern about the child’s ASD behaviors were associated with lower Condition Management Ability and higher Condition Management Effort. In addition, older caregiver age and lower social support were associated with lower Condition Management Ability. The quantitative and qualitative data were integrated to define three patterns of family management. This integrated analysis revealed that child characteristics (ASD behaviors, sleep disturbances, aggression, self-injury) and the caregiver’s social support influenced how families of children with ASD approach daily management of their child’s health and behavior. The findings from this dissertation provide a roadmap for future research on family management of neurodevelopmental conditions and identify promising areas for intervention development.