This paper deals with three areas concerning early vocal development: (1) review and critique of existing experimental evidence suggesting that early vocal behavior has the properties of an operant response, (2) speculations concerning the role of non-verbal vocal behavior in early psychological development, and (3) suggestions for future research. Skinner's "Verbal Behavior" takes the position that verbal behavior could be analyzed within operant conditioning frameworks. Chomsky argues that the system which Skinner proposes is too simplistic to account for the intricacies of human speech. Other work reviewed covers conditioned vocal responses, conditioned response differentiation, reinforcer effectiveness, and the relationship between age and conditionability. Speculation about the role of early vocal responses includes a discussion of Watson's hypothesis that the human infant is structured from birth for the processing of response-contingent information and that at least two response-contingent sequences must occur within the infant's memory span in order for him to develop an initial awareness that his responses resulted in the change in external stimulation. It is suggested that the role of response-contingent stimulation on vocal development and its long-term consequences on vocal behavior warrants further investigation. (CK)