This paper explores the roots of the concept of mutual adaptation in the literature of cognitive psychology, anthropology, biology, organizational behavior, and policy analysis. It is said that while educational researchers use the concept, their neglect of the literature on it is due, in part, to contradictory definitions of mutual adaptation as both a static and dynamic phenomenon. Mutual adaptation is then explored, based on Piaget's definition of adaptation as a balance between assimilation and accommodation. Writings on individual adaptation of information and of practices are likened to the process described by Piaget. This psychologist's basic conceptualization also is applied to adaptation by school systems, schools, and groups of teachers. Finally, literature focusing on the mutual reinforcement of individual and collective adaptation processes is reviewed, and definitions for various terms are proposed. (Author/GC)