Longitudinal videotape recordings of six young children with autism and six age- and language-matched children with Down syndrome in structured play with their mothers at home were coded for the focus of the child's visual attention for four bimonthly visits and for facial affect for two of the four visits. The main finding was that the children with autism showed reduced expression of positive affect in a familiar social context. The autistic group attended to the mother's face and the researchers only about half as much as the Down syndrome group, but these differences did not reach statistical significance. Compared to the Down syndrome group, the autistic group displayed a smaller proportion of their total positive affect toward the mother's face and toward the researcher, but only the latter group difference reached statistical significance. Although limited by the small sample size, these findings suggest that autistic children's known deficits in attention and affective responsiveness to others persist even in structured interactions with a familiar partner in the home.