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. A suite of individual differences in partners’ ability to both read the social cues of others and to send effective behavioral cues to others create dyad differences in joint attention and joint action. The present paper shows that infant and dyad differences in hand-eye coordination predict dyad differences in joint attention. In the study reported here, 51 toddlers and their parents wore head-mounted eye-trackers as they played together with objects. This method 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. However, joint attention bouts in toy play don’t depend on gaze following but rather on the coordination of gaze with hand actions on objects. Both infants and parents attend to their partner’s object manipulations and in so doing fixate the object visually attended by their partner. Thus, the present results provide evidence for another pathway to joint attention – hand following instead of gaze following. Moreover, dyad differences in joint attention are associated with dyad differences in hand following, and specifically parents’ and infants’ manual activities on objects and the within- and between-partner coordination of hands and eyes during parent-infant interactions. In particular, infants’ manual actions on objects play a critical role in organizing parentinfant joint attention to an object.