This paper offers some ideas on the types of behavior that can be considered precursors to language and that also lay the foundations for logic, mathematics, physics, etc. The paper posits the problem of whether a theory of language must be formulated before one can formulate a theory of language acquisition, or whether the reverse is true. The solution offered is the study of what is acquired at different ages, and how each stage relates to the others. This must be done by a selective study of the types of behavior that may lead to speech. After a definition of the essential features of language, prelanguage behavior may be studied. Among these behaviors is the development of what Piaget calls sensorimotor intelligence, i.e., modification and coordination of isolated action patterns present at birth. By the second year this behavior culminates in object-permanency, or the objectivization of the existence of objects and persons and their representation in the mind. A third behavior is communication, which includes vocalization, gestures, and postures. A final behavior is "babbling," which leads to the first word. The paper ends with speculation on the specific contribution of these four behaviors in the acquisition of the various levels of a particular language. (AM)