Purpose: The study explored longitudinally the course of vocabulary and general language development in a group of infants with Down syndrome (DS) compared to a group of typically developing (TD) infants matched on nonverbal mental ability (NVMA). Method: We compared the vocabulary and general language trajectories of the two groups in two ways: (a) at three time points during a 12-month period and (b) at two time points when the groups had made equal progress in NVMA (a period of 6 months for the TD infants vs. 12 months for the infants with DS). Results: The TD group had overtaken the DS group on all general language and vocabulary measures by the end of the 12-month period. However, expressive communication and expressive vocabulary were developing at the same rate and level in the two groups when examined over a period in which the two groups were matched in gains in NVMA. Furthermore, the infants with DS showed a receptive language advantage over the TD group; this group's auditory comprehension and receptive vocabulary scores were superior to those of the TD group at both time points when NVMA was accounted for. Conclusion: The results shed light on the widely reported discrepancy between expressive and receptive language in individuals with DS. Although infants with DS appear to be developing language skills more slowly than chronological age TD peers, when NVMA is taken into account, infants with DS do not have expressive language delays, and they seem to show a receptive language advantage.