This review focuses on work that deals with the mechanisms of detergent action in membrane solubilization including properties of detergents model lipid systems and detergent-protein interactions; in addition a possible sequence of events when detergents interact with biological membranes receives attention. More specific topics include: 1) properties of detergents in aqueous solutions (use in membrane studies and physical properties of detergent solutions); 2) solubilization of lipid bilayers; 3) binding of detergents to water-soluble proteins and membrane proteins (both denaturing and mild detergents); 4) effects of detergents on biological membranes (e.g. high-affinity binding and separations of lipids and proteins); and 5) detergent removal.