Importance: Families raising children on the autism spectrum experience a confluence of life factors that influence their adaptation to self-care. The Family Assessment of Quality in Self-Care Engagement (FAQ–Self-Care) focuses on unpacking the factors that influence such families’ self-care participation.  Objective: To contribute to the content validity of the FAQ–Self-Care, a tool that aims to measure the quality and extent to which families who are raising children on the autism spectrum are participating in self-care.  Design: Mixed-methods research design. Qualitative data were drawn from experts’ feedback, and the relevance of FAQ–Self-Care test items was quantitatively analyzed.  Participants: Ten occupational therapists with expertise in the fields of pediatrics and family practice were invited to review the FAQ–Self-Care. Six occupational therapists agreed to participate.  Outcomes and Measures: Occupational therapy experts reviewed the FAQ–Self-Care and rated how essential each test item is in measuring the construct of families’ self-care participation using a 4-point Likert scale. An item-level content validity index (I-CVI) and a scale-level content validity index (S-CVI) were then calculated.  Results: Twenty test items with an I-CVI score between 0.833 and 1.000 were accepted. Items 3 and 16 obtained an I-CVI score below the cutoff range (0.667) and, therefore, were revised. Additional amendments to test items were made according to the qualitative feedback provided by content experts.  Conclusions and Relevance: Initial content validity of the FAQ–Self-Care assessment tool was established. Further rigorous evaluation of validity and reliability of the FAQ–Self-Care is necessary.  What This Article Adds: The FAQ–Self-Care is a promising assessment tool that highlights the influential life factors that intersect with the self-care participation of families raising neurodiverse children on the autism spectrum.