On the basis of the examination of a number of more or less typical instances of usage, it is inferred that to say of a given syndrome, case of disordered function, or set of pathological changes that it is "psychogenic" is to say that among its causal antecedents are at least some psychic events of the sort characterized as being emotionally reinforced acts of interpretation. Some of the difficulties of applying this definition are examined, and a few concluding remarks are added on the "cash value" (in James' sense) of the concept of psychogenesis in medical practice. As for its cash value, in the literal sense, I leave it to those who practice psychotherapy to estimate—but it must be considerable.Abstract Teaser