Studies such as that of Hollinshead and Redlich of the relationship of social class and psychiatric treatment raise the question that since current psychodynamic theories may have been derived from experience with a highly selected sample, one should be cautious in generalizing about the population as a whole. As effective interpersonal communication requires similarity of linguistic conventions, and conceptual and valuational orientations, these factors may limit the applicability of psychotherapy to patients of social class similar to that of the therapist, i.e., middle and upper class. Additionally, the very principles and process of psychotherapy may be inapplicable outside that middle class from which it derived and to which it is linked by its implicit moral, epistemological, and operational precepts. These important hypotheses require substantiation, however, before introducing those modifications of the theory and practice of psychotherapy which the author implies are necessary.