The experimental analysis of behavior began as an inductively oriented, empirically based scientific field. As the field grew, its distinctive system of science--radical behaviorism--grew with it. The continuing growth of the empirical base of the field has been accompanied by the growth of the literature on radical behaviorism and its implications. In this article the case is made that radical behaviorism is more than an abstract description of the assumptions and practices of the field; it is an active area of research within the field itself, and that such theoretical research is of great importance to the development of the field. Some of the characteristics of radical behaviorism are described in brief, along with the functions of organization, clarification, and extension of various aspects of behavior-analytic science. Research examples are given from the areas of work on the system itself, behavior-analytic theory, and implications of behavior analysis for issues and findings in other fields. The unique characteristics of radical behaviorism provide an integrative and generative scientific framework for the continuing development of behavior analysis.