An understanding of human collaboration requires a level of analysis that concentrates on sensorimotor behaviors in which the behaviors of social partners continually adjust to and influence each other. In the present study, toddlers and their parents wore head-mounted eye-trackers as they played together with objects, which allowed us to track the gaze direction of each participant to determine when they attended to the same object. We found that physically active toddlers align their looking behavior with their parent, and achieve a high proportion of time spent jointly attending to the same object in toy play. Both infants and parents attend to their partner’s object manipulations and in so doing fixate the object visually attended by their partner. Moreover, dyad differences in joint attention are associated with dyad differences in hand following. Specifically, parents’ and infants’ manual activities on objects and the within- and between-partner coordination of hands and eyes.