The Meteorology Division of the National Air Pollution Control Administration and the North Carolina Air Pollution Consortium are sponsoring a symposium on Multiple Source Urban Diffusion Models scheduled for October 27–30, 1969, at the University of North Carolina. The symposium will be devoted to the presentation and discussion of papers on mathematical models of transport and diffusion of air pollution in urban areas; the relationship between sources of pollution in an urban area, its meteorology, and the air quality of the area; the analytical systems that relate to the foregoing; and the physical and meteorological basis for such urban models.