One of the major topics in the recent studies of Japanese business history has been the investigation of “zaibatsu” and since the common topic of the thirteenth national conference of the Business History Society was decided to be “Comparative Historical Study of the Zaibatsus”, the organization committee has tried to arrange the papers to be read to examine the basic characteristics of the Japanese zaibatsu in comparison with the Western big business and also to make clear the organizational and functional differences between the Japanese zaibatsus. The first paper by Yotaro Sakudo, Osaka University, “Comparative Historical Study of the Zaibatsus” presented the several problems to be discussed in the present day study on “zaibatsus” such as the zaibatsu investment strategies and their management organizations. The second paper by Professor Shigeaki Yasuoka, Doshisha University, “Characteristic Features of the Zaibatsus Capital in Comparison with the Rothschild and the Dupont”, elucidated why and how the zaibatsu families had excluded the joint-stock capital and employed the professional managers. Further Professor Yasuoka pointed out the several contrasts between the Japanese zaibatsus and the Western family enterprises by examining specific cases. The third reporter, Professor Hidemasa Morikawa of the Hosei University, read on “Business Strategy of the Japanese Zaibatsus”. He examined the process of diversification in the three Japanese zaibatsus, -Mitsui, Sumitomo and Furukawa- in an effort to confirm the differences of business strategies among them and tried to explain the differences by the difference in their decision-making processes. The fourth paper by Professor Hisashi Masaki of the Doshisha University, “Power Structure of the Japanese Zaibatsus” identified some characteristic features of the structure for control in the Japanese zaibatsus by comparing it with that of the 200 large American enterprises. The fifth reporter, Professor Moriaki Tsuchiya of the Tokyo University, read on “Economic Opportunities and Limiting Factors for the Development of Large-Scale Enterprises : Comparative Study of Japan and the United States”, discussed the volume and nature of the economic opportunities and of the human, natural and monetary resources at the different stages of the development of domestic market in the United States and Japan and explained how the Japanese zaibatsus were developed by a unique combination of the economic opportunity and resources which was entirely different from that in the United States. Through the above reports and the following comments and panel discussion, it was confirmed that the big business in Japan possessed various unique features which were derived from the socio-economic as well as cultural structures in Japan although there existed certain similarities between the zaibatsus of Japan and the large scale family enterprises of the Western countries.