Pesticides have played a significant role in increasing food production, and in view of growing worldwide food demand we can expect the use of these chemicals to increase. However, some of them have found their way into the biosphere and have been classi fied as persistent toxic chemicals. This has resulted in serious concern about environmental contamination. Since we are going to continue using chemicals, we should learn more about such aspects as their transport in the environment, the relationship of their physical-chemical properties to transport, their persistence in the biosphere, their partitioning in the biota, and toxicological and epidemiological forecasting based on physical-chemical properties. Environmental chemodynamics is the name given to a subject which deals with some of the above topics, utilizing the principles of such disciplines as chemistry, physics, systems analysis, modelling, engineering, and medical and biological sciences. To ensure the safety of the environment, we must know more about the chemodynamical behavior of pesticides and related chemi cals. The purpose of the symposium "Environmental Dynamics of Pes ticides" was to explore the concept of chemodynamics as applied to pesticides and thus may help in developing the emerging field of environmental chemodynamics. The symposium was held during the l37th National American Chemical Society Meeting at Los Angeles, California, during April, 1974. The three sessions in the sym posium were chai'red by Drs. V.H. Freed, D.G. Crosby, and R. Haque.