The Second International Symposium on Gas Transfer at Water Surfaces was held 11-14 September 1990 in Minneapolis, MN. The symposium was sponsored by the US Army Engineer Waterways Experiment Station and Professional Development and Conference Services, University of Minnesota, and focused on (a) improvements in the ability to describe the physical and chemical processes associated with gas transfer and (b) applications of process knowledge to solve engineering problems. Eighty-eight papers were selected for presentation at the symposium in the following topic areas: (a) fundamentals of physical phenomena; (b) modeling; (c) laboratory and filed measurement techniques; and (d) applications to streams and rivers, lakes and reservoirs, hydraulic structures, unit processes, water and wastewater treatment, biogeochemical cycles, seas and oceans, and artificial aeration. Controlled herein are the abstracts of those papers selected for presentation. The papers for the symposium, which are subject to peer view and acceptance, will be published by the American of Civil Engineers. Keywords: Chemical processes, Gas transfer, Physical processes, Water surfaces.