The well-established book, now in its Fourth Edition, includes the positive feedback and constructive suggestions received from academics and students alike on the third edition. While retaining the major contents of the earlier editions, this edition incorporates a new chapter on the significance and impacts of Climate Change on the practice of Geotechnical Engineering. Some of these impacts are direct, e.g., desertification, flooding. Others are indirect, e.g., population migration, agriculture. Geotechnical engineers have to be prepared with plans to mitigate the impacts of these aspects. Case histories have been included to illustrate how advance preparedness may greatly help in providing relief and rehabilitation to the people in affected regions