A comparative developmental approach was undertaken to study the play development of young children with Down syndrome and non-handicapped children during the transition from sensorimotor to representational functioning. Age-related trends in the structure of object and social play development as well as interrelationships among play maturity, cognitive functioning, and affective-social dimensions of play behaviour were considered. Although children with Down syndrome were significantly delayed in the maturity of their object and social play when compared to normal agemates, the quantity and complexity of play behaviour did not differ significantly from that of cognitively comparable non-retarded children. For both groups of children, similar developmental trends in play development were observed. Simple manipulative object play declined linearly in prevalence, whereas decontextualised symbolic play and structured social turntaking games showed a reverse trend. Despite significant differences in certain aspects of social play and interactive behaviour between groups, similar patterns of correlations among children's overall cognitive functioning and their play maturity, affective dimensions of play (quality of exploration, play engagement, positive affect), and social interactive behaviours (e.g. initiating) were observed in all children. Results attest to the coherence of play development and the organisation of symbolic behaviour during early childhood for children with Down syndrome. Implications for the use of play as a potential tool for intervention and assessment are discussed.