Increasing insight into the interfacial behaviour of surfactants has emerged during the past few years. Important advances in this area are largely due to the use of surface-specific techniques like ellipsometry, neutron reflectivity, fluorescence spectroscopy, and atomic force microscopy (AFM) for in situ studies of surfactant layer properties. This review covers recent developments in the area which have contributed to the current understanding of adsorption mechanisms and interfacial structures.