This text aims to appeal to specialist engineers with enquiring minds and, in a broader sense, to all who live in buildings, especially those in a seismically active region. While the continual development of building codes permits the design of new construction to resist earthquake loads more effectively, a major problem is that buildings which may once have conformed to past seismic codes become structurally unacceptable according to today's codes and need upgrading or "retrofitting". Poor construction methods also result in buildings that do not conform to any codes. Existing vulnerable buildings that require strengthening in earthquake-prone countries immensely outnumber all recent construction. The health of buildings thus requires assessment and rehabilitation. Seismic assessment ranges from the cataloguing of danger symptoms in individual buildings to structural analyses involving finite element procedures and refined statistical analyses incorporating expert systems, stochastic processes and predictions from available databases. Structures have to be rendered fit for earthquakes, and this book shows why and how, offering the results of cutting-edge research in the area and presenting innovative methods that enable system improvement while the structure remains in use. At the turn of the last century, builders pondering the havoc wreaked by earthquakes had scant resources to guide their reconstruction efforts. A century later, earthquakes continue tragic devastations of our cities, with one important difference - today's builders can turn to a rich literature in earthquake engineering to guide their reconstruction efforts. Topics covered in the text include seismic earthquake strong ground motion, dynamic response of structures, seismic assessment of older hazardous construction, and practical seismic rehabilitation methods derived from extensive laboratory and field research. Many of the contributions have been motivated by the tragic consequences, yet real-world experiences, of the 1999 Kocaeli and Duzce earthquakes in Turkey, and demonstrate the rapid progress that can be inspired by necessity. While the topic of this volume is especially important for Turkey and her neighbours, the lessons learned, and clearly presented here, are universal and should be studied by serious earthquake engineers worldwide.