A major metapsychological approach to conceptualizing and explaining human action within personality psychology, called the hypothetical-deductive approach, is described. A characteristic feature of this approach is that personality is conceived of as a number of nonobservable mental processes and structures constituting causal determinants of observable behavior and language. The concepts of thought, intention, and disposition, and how they relate to what people say and do, are then discussed. The conclusion is reached that although the hypothetical-deductive approach may yield an orderly, simple, and economic account of human behavior, it is based on a highly questionable conception of the nature of mind, language, and action.