This paper examines whether language development can be understood epigenetically in the same manner and based on the same principles with which Piaget has analyzed intellectual-cognitive development generally. The study is subdivided into four parts: (1) some principles in Piaget's system (the epigenetic principle, the genetic circle, and the decalage concept) are discussed in relation to language development; (2) the basic psychological functions of Piaget's theory are briefly summarized in their relationship to both cognitive and linguistic development; (3) the concept of structures or schemes as described by Piaget are examined with regard to their relevance to linguistic structures; and (4) the preverbal development of several classes of contents or concepts and their early verbal equivalents are explored. Close parallels are demonstrated between aspects of cognitive development theory and the independently established principles of language development. Since the phenomena of cognitive development appears prior to language acquisition, and since close analogies between both developments are evident, it is concluded that the prior cognitive acquisitions form the bases and molds for later linguistic advances. (Author/CS)