Surfaces play an important role in our lives. Enzymatic reactions at biological interfaces, heterogeneous catalysis, transport of contaminants in soils, and atmospheric aerosol chemistry are all controlled by interactions at surfaces. This course explores the physical and chemical phenomena that occur between the three states of matter-solid, liquid, and gas. Particular emphasis is placed on interactions with solid surfaces. Topics include, but are not limited to, reactions on surfaces, kinetics of surface reactions, binding of molecules to surfaces, and techniques of surface analysis. The importance of surface phenomena to environmental and catalytic chemistry is discussed.