Two theories of speech appear to parallel each other closely, though one (E. Nuttall) is concerned mainly with speech from a functional perspective, and the other (F. Williams and R. Naremore) presents a developmental hierarchy of language form and function. Nuttall suggests there are two main origins of speech: sounds of discomfort (cries, eventually leading to the speaker's sophisticated means of controlling his/her environment, i.e. persuasion) and sounds of pleasure (coos, the basis for communal exchange, i.e., conversation). Williams and Naremore explain the development of language form and function, characterizing the three general modes of speech as context-centered speech, sender-receiver-centered speech, and topic-centered speech. The two theories appear complementary: the empirical findings of Williams and Naremore's modes of speech continuum may offer the theory of speech behavior some scientific validity, and the theoretical explanations presented in Nuttall's theory of speech behavior may serve as a basis for additional theoretical refinements and possible new research directions for the modes of speech continuum. (One chart is included.) (SR)