This book provides both the theoretical foundation, as well as the authors' latest contributions to micromechanics and its applications in nanomechanics, nanocomposites, dislocation and thin film theories, and configurational mechanics theory.It serves primarily as a graduate level textbook, intended for first year graduate students in materials science, applied computational mechanics, nano-science and technology, and mechanical engineering. This book also serves as a research monograph by compiling recent developments in dislocation dynamics, numerical simulations of material failure, and homogenization theories.