Research programs on surfactant flooding for petroleum recovery are discussed. Research areas include the determination of microstructure of microemulsions and the effects on interfacial tension; two-phase flow studies; equations of state calculations; distribution of wetting phase; and effective medium of electrical and hydraulic conductivity in disordered porous media and composite materials. The emphasis of the research is on understanding basic physical and chemical mechanisms with the goal of transforming this knowledge into the concepts and mathematical formulations needed for engineering process design and analysis. (CBS)