An analysis of implementation of educational change distinguishes between three kinds of processes: mutual adaptation, cooptation, and nonimplementation. Mutual adaptation was defined as the process in which implementation was successful, and in which significant changes in participant attitudes, skills and behavior occurred. Implementation was characterized by a process in which project goals and methods were modified to suit the needs and interests of participants and in which participants changed to meet the requirements of the project. This paper elaborates and expands the definition of mutual adaptation to include: (1) the adaptive process of an innovative program and its implementers; and (2) the dynamic interaction between program developers and trainers, i.e., innovators on the one hand, and program implementers on the other. The conceptualization of this definition is illustrated through the study of the implementation of an innovative instructional approach called "Complex Instruction." It is demonstrated how this dynamic interaction between developers of educational innovations and its implementers has led to adaptations in the innovation, in the training model provided by the innovators, in the behaviors of the participants and in their organizational context. These adaptations have improved and strengthened the program and made it more effective. (JD)