Anxiety is recognised as one of the most common co-occurring conditions for individuals with a diagnosis on the autism spectrum, with approximately 40 % of children on the spectrum receiving a clinical diagnosis of an anxiety disorder. To date, research has tended to focus upon understanding presentation and evaluating treatment, with little focus on assessing systemic factors, such as the way that family members accommodate the anxiety. This study aimed to investigate the relationship between parent and child anxiety levels and child autism characteristics on the four domains of family accommodation; Participation, Modification, Distress, and Consequence. A community sample (n = 132) of parents of children on the spectrum completed questionnaires on their child's autism characteristics and anxiety symptomatology as well as their own levels of anxiety and family accommodation behaviours. Regression models identified specific aspects of child anxiety as well as parent anxiety as predictive of family accommodation, with the child's difficulties with uncertainty being a consistent predictor of all four domains. Clinical and research implications of this study, including the importance of understanding similarities or differences in the nature and consequence of family accommodation in children on the autism spectrum, are discussed.