Sustained attention (SA) is a critical skill in which a child is able tomaintain visual attention to an object or stimulus. The current studyemploys head-mounted eye trackers to study the cognitive processesunderlying SA by analyzing micro-level behaviors during parent-child social interactions in both typically and atypically developingchildren. Specifically, we examined the role of parent look, parenttouch, and child touch on SA duration. Results show that parent lookequally influences SA in both groups, while parent touch is morecritical for SA for TD children and the child’s own touching is morecritical for SA in children with autism spectrum disorder (ASD).Implications of different pathways to maintain SA between typicallydeveloping children and children with ASD are discussed.