The author mentions the diverse types of investigations that are today included under the general heading of psychiatric research. These include studies in clinical symptomatology, psychodynamics, personality theory, psychoanalysis, learning theory, child development, group dynamics, perception theory, sociology, cultural anthropology, genetics, psychosomatic medicine, psychotherapy, biochemistry, psychophysiology, neurophysiology, neuroanatomy, and psychological testing. The usefulness of the concept of "total personality," of exclusive dichotomies, and of multiple causality are discussed.