Much of the published research in infant speech perception has emphasized how well infants have done with a number of speech contrasts, and have noted similarities in pattern of discrimination of adults and infants. Often it has been suggested that infants begin life with the ability to perceive any speech contrast, and that the process of acquiring a language involves inhibition of the ability to perceive contrasts not present in the target language. Indeed some studies have shown infants able to discriminate contrasts on which adults fail if the contrasts are not drawn from the native language of the adults. Other studies, however, have suggested that infants may not always be so perceptually capable. The present work focusses on the stop-glide contrast. The results are inconsistent with the prevalent view and with previously reported studies on the perception of the stop-glide contrast by infants. The results indicate that in a vigilance paradigm adapted for both infant and adult testing, infants perform poorly on the contrasts when compared with adults. Furthermore the pattern of relative perception observed in the adults on stimuli with long or short vowels is quite unlike that of the infants. It is concluded that much work remains in order to evaluate the relative performance of infants and adults in speech perception, since it appears that changes in experimental paradigm or particular stimulus parameters may affect outcomes in fundamental ways.