The volume collects the contributions presented at the second meeting on Unilateral Problems, organized by CISM and held near Udine in June 1985. It gives an updated account of the state-of-the-art in the field of unilateral problems, with an outlook on open problems and on perspectives of application to structural analysis. The topic is presently the object of growing interest and is undergoing very rapid development. One of the most noticeable characteristics of unilateral problems is their interdisciplinary nature; they involve sophisticated mathematics, fundamental questions in mechanics, modern techniques in numerical analysis, re-inspection of the present knowledge of physical phenomena, and engineering applications. This volume succeeds in collecting and coordinating contributions from all these areas. For this reason, it is an excellent source of information for researchers working in the field.