This study examined the relationship between mental state term use in children with autism spectrum disorder (ASD) and typically developing (TD) children engaged in play. Expression of mental state terms was used as an indicator of theory of mind (ToM) skills. Archived data were used to compare mental state term use for five ASD-TD dyads engaged in various play contexts. During imaginative play, children with ASD used fewer cognition mental state terms than TD children but used a similar number of emotion mental state terms. In combination play, both groups used similar numbers of cognition and emotion mental state terms. Play context implicates use of mental state terms in expression in children with ASD. Scaffolding use of mental state terms during play may provide an opportunity for children to use more advanced levels of ToM, including cognitive mental state term expression, when engaged with peers.