During the last decade, various powerful experimental tools have been developed, such as small angle X-ray and neutron scattering, X-ray and neutron reflection from interfaces, neutron spin-echo spectroscopy and quasi-elastic multiple light scattering and large scale computer simulations. Due to the rapid progress brought about by these techniques, one wittnesses a resurgence of interest in the physicochemical properties of colloise, surfactants and macromolecules in solution. Although these disciplines have a long history, they are at present rapidly rapidly transforming into a new, interdisciplinary research area known as complex liquids of soft condensed matter physics: names that reflect the considerable involvement of the chemical and condensed matter physicists. This book is based on lectures given at NATO ASI held in the summer of 1991 and discusses these new developments, both in theory and experiment.