Through a solid assessment of parallel computing hardware issues, parallel programming practices, and implementation of key methods, this book enables readers to develop and implement efficient quantum chemistry software capable of utilizing large-scale parallel computers. It addresses specific parallel programming challenges facing quantum chemists not covered in other resources, including message-passing, multi-threading, and parallel computer architectures. The book presents in-depth performance analyses of several quantum chemistry procedures, such as the Hartree-Fock method and Møller-Plesset perturbation theory, and contains many program examples written in the C programming language.