It is possible to approach the philosophy, sociology, and social psychology of George H. Mead in at least two major ways, depending on whether his thought is considered to be a systematic unity in which all central themes mesh internally and consistently, or whether Mead's work is comprehended as a series of significant efforts to explore the nature of social reality from separate though genetically related perspectives which reveal serious internal deviations and tensions. Choice of approach is not an arbitrary matter: both modes of investigating Mead's ideas necessarily have their limitations; but it is our conviction that the profound and original themes Mead explored in his intellectual life-time can best be grasped by choosing to follow the development in his thought that led him, in our view, from 'social behaviorism" to a position which transcends behaviorism of any sort. The validity and value of our selected mode of procedure can, of course, be demonstrated only through an extended presentation. The exposition of the decisive and variant aspects of Mead's thought through a developmental analysis is the necessary preparation for the critical evaluation of his thought.