The book provides the state-of -the-art approach to various classical methods of solid and structural mechanics as well as the finite element method, which is globally accepted as the most powerful computational tool ever devised to solve practical engineering problems. It will cover work and energy principles of solid and structural mechanics (eg., unit load displacement method; Castiglianos' Theorems; and Betti and Maxwell's theorems of reciprocity), traditional variational methods like Ritz, Galerkin, collocation, and least-squares variational methods of engineering and applied science, and the finite element method; and applications of these methods to bars, trusses, beams, and plate structures. This third edition includes an extensively reorganized and includes a large amount of new material including a new chapter ten and is devoted to functionally graded beams and plates, with up to date developments in the field. Chapter 1 is a combination of the first two chapters of the previous edition. Chapter 2 on review of equations of solid mechanics is revised significantly to provide pertinent equations, including classical and Timoshenko beam theories and the von Karman nonlinear theories; Chapters 3 through 9 in the new edition correspond to chapter 4 thru 10 of the second edition, but with additional explanations, examples, and exercise problems. In general, all of the chapters in the third edition contain additional explanations, detailed example problems, and additional exercise problems. The new edition more than replaces the second edition.