Current economics often dictate the use of structures well beyond their design lives. Today, there is an increased reliance on nondestructive evaluation (NDE) to provide accurate data about the health of materials in these aging systems. Examples of such structures include aircraft, bridges, nuclear reactors, roads, ships, industrial manufacturing facilities, storage vessels for both toxic and nontoxic substances, electronic hardware, etc. This book looks at ways to develop new NDE techniques for aging materials. Special emphasis is given to the structural health of concrete, defects in high-strength aircraft materials and the characterization of steels in nuclear reactors. One intriguing new technology, borrowed from the semiconductor industry, is the use of very small micro-electro-mechanical systems (MEMS) to monitor materials properties in situ. Using these devices in networks should permit both real-time monitoring of materials properties during operation and the anticipation of component failure. The book also explores the many potentially fertile collaborative research opportunities between NDE and noninvasive medical diagnostic procedures.