Background:Parent-child play interactions offer an important avenue for supporting social development in children with autism spectrum disorder (ASD). Musical play is a natural and ubiquitous form of parent-child play. As a familiar, reinforcing, and predictable activity, musical play may support parent-child interactions by scaffolding children's attention to the play activities, while also providing parents with a familiar and accessible context to promote parental responsiveness. However, musical play may also impede interactions due to its sensory and repetitive components. Method:12 parent-child dyads of preschoolers with ASD were video-recorded during a ten-minute play session that included musical and non-musical toys. Interactions were coded for parent and child musical engagement, as well as parental responsiveness. Results:Parent-child dyads varied in their amount of musical engagement during play, which was not related to children's language level. Overall, parents showed similar levels of responsiveness to children's play across musical and non-musical activities, but type of parental responsiveness differed depending on the play context. Parents provided significantly more physical play responses and significantly fewer verbal responses during musical vs. non-musical engagement with their child. Conclusions:There are substantial individual differences in children with ASD's musical engagement during a parent-child free play. Children's musical engagement impacted type of parental responsiveness, which may relate to the familiarity, accessibility, and sensory nature of musical play/toys. Results suggest that musical play/toys can both support and hinder different types of parental responsiveness with implications for incorporation of musical activities into interventions.