It is the contention here that the "prelinguistic" period is an important phase of the language acquisition process. Accordingly the research reported represents an attempt to begin mapping out the types of linguistically relevant information to which a young child attends. Specifically it is hypothesized that young children are especially tuned to the linguistic information carried in the supra-segmental system of language (intonation, stress, and juncture) and that detection of such information eventually leads the child to other aspects of language patterning. The participants in the study consisted of 20 4-month-old and 20 8-month-old infants. The subjects were divided into four groups of 10 infants each, and an habituation-dishabituation paradigm was used to study their discrimination of terminal contour. The results suggest that normal falling and rising intonation contours, including the stress marker, can be discriminated by at least 8 months. The data indicate that neither group of 4-month-old infants was able to distinguish between the presented forms. Exactly when the ability to discriminate between these features appears is not clear, except that it develops somewhere between 4 and 8 months old. Several questions remain to be answered, and further research with more sensitive habituation and conditioning procedures is in process. (Author/LG)