In this paper we will present an overview of the legacy of Roman Jakobson (1941/1968, 1971) in the fields of developmental and clinical phonology, concentrating especially on theories that have continued his communication oriented approach involving the phoneme, distinctive features and markedness theory. We will specifically show how André Martinet (1955) shifted the emphasis from the teleological focus of Prague School phonology to a more human oriented, ‘therapeutic’ phonology based on the principles of asymmetry and economy of effort We will first present the theory of Phonology as Human Behavior, developed by William Diver and his students, which combines aspects of the communication factor inherent in Prague School phonology with aspects of the human factor inherent in Martinet's diachronic phonology. The major parameters of the theory are presented according to the definition of language as a sign system used by human beings to communicate. The fundamental axiom underlying the theory is that language represents a struggle between the desire for maximum communication (the communication factor) with minimal effort (the human factor). This principle was originally presented as a means to explain the non-random distribution of phonemes in various languages. It is further maintained that developmental and clinical phonology represent a more extreme version of this “mini-max” struggle where the human factor clearly overrides the communication factor as a means of explaining the non-random distribution of developmental and clinical data.