Adult-child co-viewing is thought to affect children’s learning and development positively, by providing resources for making meaning. Adult responses to the content being viewed may encouraged sustained attention and develop vocabulary and content knowledge. This study (of 146 preschoolers from three Head Start programs) examined how joint media engagement might influence low-income children’s vocabulary and story comprehension. Each child view 4 educational program videos – two alone, and two with an adult co-viewer who laughed playfully at lines in the shows pointed out interesting moments, said vocabulary words, and engaged with the child. Eye-tracking technology was used to measure the children’s attention. Co-viewing was not found to have a main effect on vocabulary learning, but did interact significantly with percent fixation duration. Greater attention in co-viewing was positively associated with higher vocabulary scores and comprehension.