B. G. Marsden Harvard-Smithsonian Center for Astrophysics Cambridge, MA 02138, U.S.A. !AU Symposium No. 81, "Dynamics of the Solar System", was held at the Hydrographic Office, Tokyo, Japan, during 23-26 May 1978. The Sym­ posium was cosponsored by COSPAR and IUTAM, and generous financial sup­ port was also provided by the Japan Society for the Promotion of Science. !AU sponsorship was through Commissions 4, 7 and 20, and the Scientific Organizing Committee consisted of the current Presidents, Vice Presi­ dents and immediate Past Presidents of these Commissions: V. K. Abalakin, R. L. Duncombe, Y. Kozai, L. Kresak, B. G. Marsden (Chairman), P. J. Message, A. M. Sinzi, G. Sitarski and V. G. Szebehely. There were 64 participants from 15 countries, and 55 invited and contributed papers were read. The papers covered all branches of re­ search on solar-system dynamics, and the eight sessions (chaired by Y. Kozai, V. G. Szebehely, W. Fricke, A. M. Sinzi, G. Sitarski, B. G.