This book is intended to serve as an undergraduate textbook on mechanics of solids for the engineering students. It provides conceptually sound and rigorous foundation of three-dimensional concepts of stress, strain, constitutive relations, yield criteria, brittle fracture and fatigue failure; and energy-related theorems. Subsequently, this theory is applied rigorously to the elastic and elastic-plastic analyses of bars under axial force, twisting moment, bending moment, general loading and buckling of columns. This textbook also covers visco-elastic response of bars, standard tension and compression tests. The book includes pedagogical features like worked out examples, chapter reviews and end-of-chapter exercises to aid in self-learning of the students. This book will be highly useful for the undergraduate engineering students as a textbook and reference book for postgraduate students/researchers.