Play is a powerful influence on children's learning and parents can provide opportunities to learn specific content by scaffolding children's play. Parent-child synchrony (i.e., harmony, reciprocity and responsiveness in interactions) is a component of parent-child interactions that is not well characterized in studies of play. We tested whether children's executive function relates to mother-child synchrony during physical and digital play in sixty mother-child dyads. Mother-child synchrony did not relate to children's executive function or differ by play type (physical, digital), though during digital play mother-child synchrony was higher for girls relative to boys. The findings suggest that mother-child synchrony is not influenced by children's executive function and physical and digital play can be similarly beneficial in offering the opportunity for responsive, reciprocal, dynamic interactions. The sex difference suggests that further factors should be explored as influences of play synchrony. [This paper was published in "Trends in Neuroscience and Education" v29 2022.]