IAU Symposium No. 81, “Dynamics of the Solar System”, was held at the Hydrographic Office, Tokyo, Japan, during 23–26 May 1978. The Symposium was cosponsored by COSPAR and IUTAM, and generous financial support was also provided by the Japan Society for the Promotion of Science. IAU sponsorship was through Commissions 4, 7 and 20, and the Scientific Organizing Committee consisted of the current Presidents, Vice Presidents and immediate Past Presidents of these Commissions: V. K. Abalakln, R. L. Duncombe, Y. Kozai, L. Kresfik, B. G. Marsden (Chairman), P. J. Message, A. M. Sinzi, G. Sitarski and V. G. Szebehely.