Infant-carrying behaviour was observed in two families of captive golden-headed lion tamarins. Although the young were raised in almost identical social situations, we found a reversed involvement of mother-father pairs in the amount of time they carried their offspring. In one case, the parental division of carrying behaviour was consistent with the standard description for callitrichids in that the adult male was the primary carrier. In the other family, the mother carried the infant considerably more than the male. Comparison of transfer initiations and transfer times showed that maternal choice operated. It is suggested that maternal behavior may depend primarily on the female’s physical and hormonal conditio