The fourth edition of this book A Textbook of Strength of Materials contains twenty five chapters. This edition has been thoroughly revised and made up-to-date. A large number of numerical problems from different B.E. degree examinations have been added with solution at proper places. At the end of each chapter, highlights, theoretical questions and many unsolved numerical problems with answers have been given for the students to practice them. Three advanced topics--stresses due to rotation in thin and thick cylinders, bending of curved bars and theories of failures of the materials have also been added. These chapters have been written in such a simple and easy-to-follow language that even an average student can understand them easily by self-study. A large number of Objective Type Multiple Choice Questions, asked in the most of the competitive examinations, have been incorporated in this edition with answers and explanations to make this edition more useful for competitive examinations.