The symposium was jointly organized by the International Association of Meteorology and Atmospheric Physics (IAMAP) and by the International Association of Geomagnetism and Aeronomy (IAGA). It was cosponsored by SCOSTEP, COSPAR, and by the following IAMAP Commissions: ICACGP, IOC, and IRC. The large number of contributions, about 160 papers presented in 11 half-day sessions, reflects the increasing activity in middle atmosphere research and the growing interest of scientists from many nations, including the developing countries, in efficient communications in this field. The sessions contained contributions about (1) solar UV flux, photochemical processes, and related chemistry; (2) remote sensing; (3) dynamics, including troposphere coupling; (4) the strato-meso-thermosphere system and solar-terrestrial relationships; (5) climatology of the middle atmosphere; (6) gravity waves, turbulence, and related transport; (7) modeling, including the radiation budget; (8) trace species; (9) ions and aerosols; (10) electrodynamics; and (11) aeronomic phenomena in the mesopause region, including noctilucent clouds.