Polymer addition to an aqueous surfactant solution causes phase separation when the solution is initially a single liquid crystalline phase or a dispersion of liquid crystal in brine but not when the solution is an isotropic phase containing no liquid crystal. The resistance of randomly coiled polymer molecules to configurational change is the underlying cause of the phase separation. These results provide a basis for understanding and subsequently eliminating phase separation due to polymer-surfactant interactions in micellar-polymer recovery processes. A theory of drop size in microemulsions has been developed which includes an improved model of the surfactant films at the drop surfaces. Its most significant novel feature is a lattice model of the hydrocarbon chain region of the film which allows the amount of oil penetrating the film to be determined. The first portion of the theory discussed herein deals with nonionic surfactants. It predicts, among other things, the effect of oil chain length on drop size and inversion conditions. The theory thus offers good prospects of explaining for the first time the observed alkane carbon number effect on microemulsion behavior. A novel concept for reducing sensitivity of ultralow interfacial tensions to salinity is being investigated. It is discussed fully in an appendix to the report.