The author's purpose in this article is to discuss the aspects of language (especially the development of language in children) to which biological concepts are most appropriately applied. While results of past studies would seem to show that language development is contingent on specific language training, it is important to distinguish between what the child actually does and what he can do. Comparative studies of children raised by deaf and hearing parents indicate that "the earliest development of human sounds appears to be relatively independent of the amount, nature, or timing of the sounds made by the parents." The author feels that "language capacity follows its own natural history." The child's language activity "can be limited by his environmental circumstances, but the underlying capacity is not easily arrested. Impoverished environments are not conducive to good language development, but good language development is not contingent on specific training measures." Evidence also indicates that inheritance and general cognitive growth are important factors in language development and that there is a critical age limit for primary language acquisition. Language is not the cause of cognition or a static product of the mind but rather a profoundly integrated activity which will give us clues to the operating principles of the brain. (JD)