We examined the effects of joint attention for object learning in 5- and 7-month-old infants. Infants interacted with an adult social partner who taught them about a novel toy in two conditions. In the "Joint Attention" condition, the adult spoke about the toy while alternating gaze between the infant and the toy, while in the "Object Only" condition, the adult looked to the toy and to a spot on the ceiling, but never at the infant. In the test trials following each social interaction, we presented infants with the "familiarization" toy and a novel toy, and monitored looking times to each object. We found that 7-month-olds looked significantly longer to the novel toy following the "Joint Attention" relative to the "Object Only" condition, while 5-month-old infants did not show a significant difference across conditions. We interpret these results to suggest that joint attention facilitated 7-month-old infants' encoding of information about the familiarization object. Implications for the ontogeny of infant learning in joint attention contexts are discussed. (Contains 4 figures.)