To what extent do social practitioners use scientific knowledge on their jobs? This delicate question can best be answered by observing them in practice. Lacking this possibility, we might consider the quality of their professional training. Schools for practitioners give as a matter of course more or less extensive training in basic social science. Much specific knowledge from the school years might be only vaguely remembered in later practice, but here as elsewhere, the rule holds that education is what is left when we have forgotten everything we learned. That is, long after the specific pieces of knowledge are forgotten, certain generalizations and habits of thought remain. For example, the social 24worker in an adoption agency may forget much about the detailed information concerning heredity and might not be able to recall a single scientific study of the topic, but the generalization that “acquired characteristics are not hereditary” will remain with her and be of considerable use in her professional practice. No judgment about the knowledge of professionals should overlook such latent effects of past scientific instruction.