This compact treatment of the basic theory of nuclear forces, structures, and reactions bases its explanations almost entirely on the familiar results of nonrelativistic quantum theory. Suitable for advanced undergraduates and graduate students, it presents careful and concise discussions of experimental ideas. The three-part treatment begins with the descriptive theory of nuclei, covering basic facts, including size, spins and statistics, and beta-disintegration and the neutrino. The second part explores quantitative theory of nuclear forces, covering physical properties of protons, neutrons, and deuterons; scattering; and effects of molecular binding and of non-central forces. The final section examines complex nuclei and beta-decay, including nuclear reactions, scattering, and beta-disintegration.