The present study assessed mastery behaviors in toddlers with physical impairment during object and social play interaction with their parents. Poor mastery motivation in object play of children with physical impairments has been attributed to difficulty in independently structuring tasks, limited experience in play effectiveness, and frequent failure with tasks. Samples of free object and social play between 25 parents and toddlers with physical impairments were analyzed to compare mastery behaviors during social and object play, and the relationship of these mastery behaviors to other developmental skills. Children attended to task more and were more persistent during object play than during social play. Social interchange, referencing, and displays of affect were more frequent during social play. Both cognitive and receptive language scores were positively correlated with exploration and persistence. However, children's motor skills were positively correlated with exploration and persistence, which suggests that persistence measures alone are insufficient as metrics of mastery motivation in children with physical impairments without considering other social and contextual metrics. (Contains 4 tables.)