Two sections in this survey of research on conceptualization are devoted to "Recent Conceptual Studies in the Behaviourist Mould" and "Main Stream of Ontogenetic Studies of Conceptualization." Under Section I, topics investigated are behaviourist approaches to the conceptual process, conceptual problems, and developmental studies. In Section II, subjects include introduction to Piaget's work, mathematical and scientific concepts (number, quantity, weight, area, volume, space, time, velocity, causality, and logical thinking), conceptualization in the mentally and physically handicapped, educational aspects, and social, self, and class concepts. A concluding chapter deals with general aspects of conceptualization. A lengthy bibliography is also included. (DO)