REVIEWED ARE THE PSYCHOLOGICAL STUDIES OF CONCEPT LEARNING AS THEY RELATE TO CONCEPT TEACHING. AN ANALYSIS IS MADE OF THE NATURE OF CONCEPT LEARNING AS IT IS STUDIED IN THE PSYCHOLOGIST'S LABORATORY, INCLUDING THE NATURE OF CONCEPT TASKS AS THEY APPEAR IN SUBJECT MATTER LEARNING. THE PRIMARY KINDS OF CONCEPT LEARNING SITUATIONS, INCLUDING THE VARIABLES INVOLVED, THAT HAVE BEEN STUDIED BY PSYCHOLOGISTS ARE DESCRIBED AND THE PROPERTIES OF CONCEPTS THAT APPEAR TO BE RELEVANT TO SCHOOL SUBJECT MATTER WHICH NEED FURTHER STUDY ARE LISTED. THERE ARE TWO MAJOR CONCLUSIONS. ONE IS THAT THE CONCEPT FORMATION STUDIES TO DATE ARE NOT INAPPLICABLE TO TEACHING, BUT THAT THEY ARE APPLICABLE TO ONLY A NARROW DOMAIN OF SUBJECT MATTER. THE OTHER IS THAT THE LACK OF ANALYSES OF THE NATURE OF COMPETENCE IN DIFFERENT CONCEPTUAL TASKS, THE RIGIDITY OF THE EXPERIMENTAL PROCEDURES IN ADAPTING TO RESPONSE HISTORIES, THE NEGLECT OF INDIVIDUAL DIFFERENCE-LEARNING PROCESS INTERACTIONS, AND THE LACK OF STRONG THEORIES HAVE KEPT THE FIELD MUCH LESS RELEVANT THAN IT SHOULD BE TO GENERATE RESEARCH APPLICABLE TO THE PROBLEMS OF HOW CONCEPTS ARE LEARNED AND HOW THEY SHOULD BE TAUGHT. AN EXTENSIVE BIBLIOGRAPHY IS PROVIDED. THIS DOCUMENT IS A PREPRINT OF A CHAPTER TO APPEAR IN "RESEARCH APPROACHES TO SCHOOL-SUBJECT LEARNING," R. GAGNE (ED.), TO BE PUBLISHED BY F. E. PEACOCK PUBLISHERS, ITASCA, ILLINOIS, 1968. THIS DOCUMENT IS AVAILABLE FROM THE UNIVERSITY OF PITTSBURGH, LEARNING RESEARCH AND DEVELOPMENT CENTER, PENNSYLVANIA. (DS)