This book deals with multiple repeated analyses (reanalysis) of structures. Reanalysis is needed in many problems of structural analysis, design and optimization. It is related to a wide range of applications in Aerospace - gineering, Civil Engineering, Mechanical Engineering and Naval Archit- ture. The book was developed while I was teaching graduate courses on analysis, design and optimization of structures, in the United States, C- ada, Europe and Israel. It summarizes many years of research and dev- opments in these areas. The purpose of the book is to collect together the main results of this work and to present them in a unified approach. It meets the need for a general text covering the basic concepts as well as - cent developments on reanalysis of structures. This should prove useful to students, researchers, consultants and practicing engineers involved in structural analysis and design. Other books on structural analysis do not cover most of the topics presented in the book. Early developments on this subject are introduced in a previous book by the author (Design-Oriented Analysis of Structures, Kluwer Academic Publishers, Dordrecht 2002). In general, the structural response cannot be expressed explicitly in terms of the structure properties, and structural analysis involves solution of a set of simultaneous equations. Reanalysis methods are intended to analyze efficiently structures that are modified due to changes in the str- ture properties. The object is to evaluate the structural response (e. g.