Many inverse problems of great practical importance are found in engineering mechanics alone, and there is currently a dramatic increase of research activity in this area. This book contains about 65 selected papers by authors from Europe, Asia and America. The overall contents reflect the state of the art in this particular applied research area. The main topics are: Unknown shape determination; Identification of material properties; System determination; Boundary conditions and source identification; Defect identification; Mathematical and computational aspects; Experimental strategy.