Although often associated with the experimental analysis of behavior, behavior theory and philosophy also is concerned with those concepts that govern the practice and application of the science of behavior. Increasingly, behavior theory and philosophy also includes the interpretation of classes of behavior that are either presently beyond the methods of scientific study or simply have not yet been studied using the methods of the experimental analysis of behavior. The experimental analysis of behavior, applied behavior analysis, and interpretive analyses of behavior together form the corpus of concepts that constitute behavioral psychology. Philosophy itself constitutes a fourth conceptual level that provides a wellspring of constructs and concepts on which the content areas of behavior analysis draw. Philosophical principles also serve a watchdog function whereby behavioral accounts of human action are frequently challenged, but more often shaped. This volume has several goals with respect to the interplay between philosophy and behavioral psychology's experimental, applied, and interpretive levels of knowing. The first is to examine core principles in the philosophy of science, as they are interpreted by and relate to behavioral psychology. The second goal is to examine how these core principles interact with different problem areas in the study of human behavior, especially those of application and interpretation. The third, broader, goal is to convey how experimental, applied, and interpretive analyses complement one another to advance the understanding of behavior and, in so doing, also the philosophy of science.