This study examined the importance of target location (within vs. outside the visual field) on the relation between responding to joint attention and subsequent language development in 47 normally developing infants. The results supported a developmental progression in the infants' ability to locate targets from within to outside the visual field. In addition, individual differences in 15-month-old infants' ability to correctly locate targets outside the visual field was a unique predictor of expressive language at 24 months. Infants' ability to locate targets outside the visual field may demonstrate increasing capacities for attention regulation, representational thinking, and social cognition that may facilitate language learning. The implications of this study are discussed with regard to the usefulness of measures of responding to joint attention for identifying early language and developmental delays.