BackgroundThe Developmental, Individual-differences, Relationship-based model (DIR/Floortime) is one of the well-known therapies for autism spectrum disorder (ASD), in which its main principle is to promote holistic development of an individual and relationships between the caregivers and children. Parental engagement is an essential element to DIR/Floortime treatment and involved with various factors. Finding those supporting factors and eliminating factors that might be an obstacle for parental engagement are essential for children with ASD to receive the full benefits of treatment.AimTo examine the association between parents, children and provider and service factors with parental engagement in DIR/Floortime treatment.MethodsThis is a cross-sectional study of parents with children aged 2–12 years who were diagnosed with ASD. Data were collected using a parent, child, provider and service factors questionnaire. Patient Health Questionaire-9, Clinical Global Impressions-Severity and Childhood Autism Rating Scale were also used to collect data. For parent engagement in DIR/Floortime, we evaluated quality of parental engagement in DIR/Floortime and parent application of DIR/Floortime techniques at home. Finally, Clinical Global Impressions-Improvement and Functional Emotional Developmental Level were used to assess child development.ResultsParents who were married, had lower income and higher knowledge of DIR/Floortime theory were more likely to have higher parent engagement (χ2=4.43, p=0.035; χ2=13.1, p<0.001 and χ2=4.06, p=0.044 respectively). Furthermore, severity of the diagnosis and the continuation of the treatment significantly correlated with parent engagement (χ2=5.83, p=0.016  and χ2=4.72, p=0.030 respectively). It was found that parents who applied the techniques for more than 1  hour/day, or had a high-quality parent engagement, significantly correlated with better improvement in child development (t=−2.03, p=0.049; t=−2.00, p=0.053, respectively).ConclusionFactors associated with parents, children, and provider and service factors had a significant correlation with parent engagement in DIR/Floortime in which children whose parents had more engagement in DIR/Floortime techniques had better improvement in child development.