Education for the practice of psychology has evolved through a preprofessional phase, a scientist–professional phase, and a professional phase, in which each successive pattern of education complements but does not replace the prior pattern. Each phase of development is grounded in its own assumptions about relations between research and practice. The concepts of practice as applied science, reciprocity of science and profession, and practice as disciplined inquiry are considered. The concept of practice as disciplined inquiry is appropriate to the education of professional psychologists. Complementarity of basic research, applied research, and professional service requires appreciation of fundamental differences as well as similarities in the structure of research and practice.