Between the area known as surface science (which mainly deals with single crystal surfaces) and the vast area of the surface properties of dispersed solids (knowledge of which is widely applied in catalysis and materials science) there is still a remarkably wide, although gradually decreasing, gap. Because fundamental physico-chemical problems are involved, this borderline area needs to be explored. With this objective, the Trieste meeting brought together specialists with a variety of origins and backgrounds, with the aim of stimulating the growth of our knowledge in this area. This proceedings volume contains ninety-three papers, comprising plenary lectures, short communications, and poster contributions on the applications of physical and theoretical methods to perfect and dispersed (microcrystalline and amorphous) metals, oxides, and mixed systems. Special emphasis is given to metal-support interfaces. The book thus provides a wealth of up-to-date information on a topic of current interest which will be of value to researchers who use chemical and/or physical methods for the study of surfaces.