This graduate-level text presents the fundamental physics of solid-state lasers, including the basis of laser action and the optical and electronic properties of laser materials. Some knowledge of quantum mechanics and solid-state physics is assumed, but the discussion is as self-contained as possible, making the book an excellent reference as well as useful for independent study. After an overview of the topic, the book is divided into two parts. The first begins with a review of the quantum mechanics and solid-state physics, spectroscopy, and crystal field theory; it then treats the quantum theory of radiation, the emission and absorption of radiation, and nonlinear optics; it concludes with discussions of lattice vibrations and ion-ion interactions and of their effects on optical properties and laser action. The second part treats specific solid-state laser materials, the protypical ruby and Nd-YAG systems being treated in greatest detail; it concludes with a discussion of novel and non-standard materials.