Nuclear Reactions deals with the mechanisms of nuclear reactions and covers topics ranging from quantum mechanics and the compound nucleus to the optical model, nuclear structure and nuclear forces, and direct interactions. The structure of the atomic nucleus and capture of slow neutrons are also discussed, along with nuclear reactions at high energies, neutron capture and nuclear constitution, and elastic and inelastic diffraction scattering. This book is comprised of 17 chapters and begins with an overview of early successes and difficulties experienced by nuclear physics as a discipline, paying particular attention to early applications of quantum mechanics and reactions with neutrons. The next chapter explores the compound nuclear and considers the theory of Breit and Wigner, resonances in nuclear reactions, and the statistical model or compound nucleus model. The reader is methodically introduced to the optical model and elastic scattering experiments; nuclear structure and nuclear forces; and direct interactions. The remaining chapters look at the theory of the effect of resonance levels on artificial disintegration; fluctuations of nuclear reaction widths; scattering of high-energy neutrons by nuclei; and regularities in the total cross-sections for fast neutrons. This monograph will be a useful resource for nuclear scientists and physicists as well as undergraduate students who have taken a first course in quantum mechanics.