Viewing the studies on development of thinking from 1964 through 1965, the following topics were discussed; 1.Studies on concept learning and problem-solving 1)Analysis of development of concept formation processes by means of the transfer of learning 2)Analysis of conditions of concept formation 3)Characteristics of stimuli in concept formation 4)Inference and other thinking processes 2.Studies on cognitive development 1)Studies on conservation 2)Transitivity 3)Studies on number concept 3.Method of approach