'This Symposium comprises several interrelated parts aimed at familiarizing chemists, physicists, engineers and managers with the latest developments in all aspects of flammability and fire retardants. My assigned topic suggests that my presentation should accomplish this task from a forestry perspective. Firstly, I will consider, in general terms, the effects of weather, fuel and topography on forest fire behavior. Secondly, I will discuss the application and effectiveness of commonly-used chemical fire retardants in containing and extinguishing wildland fires in northern forests, including their effects on the environment. In particular, I have tried to isolate and discuss those factors and effects which optimize the capabilities of fire retardants in different fuel and fire situations. As used in this paper, the term fire retardant refers to retardant chemicals which, when applied to forest fuels, alter the combustion process to produc,e less flammable products whiie increasing the amount of nonflammable products (George and Blakely, 1972). In contrast, water and water-based 'short-term retardants' rely primarily on their cooling action to slow fire spread and they lose their effectiveness after the water has evaporated.'