The illness perception questionnaire (IPQ) and its revision (IPQ-R) measure perceptions about health-related diagnoses and the influence of cognitions on coping. In this study, the factor structure of a version revised for use with autism spectrum disorder (ASD) was investigated with a sample of parents (n = 361) whose children have ASD. Subsequently, multidimensional item response theory was used to evaluate item and subscale properties. Results indicated items from five of the seven IPQ-R-ASD scales loaded as expected, though subscales related to control were not distinct. Additionally, parents' response patterns were evaluated and discussed. Use of this measure in ASD-focused research may enhance understanding of how parents' cognitions of their child's ASD impacts treatment selection, treatment implementation, and overall family well-being.