By the end of the 1970s, crystalline lasers were widely used in science, engineering, medicine, and technology. The types of lasers used have continued to grow in number to include newly discovered crystalline hosts, previously known compounds generating at other spectral wavelengths, and broadband tunable stimulated emission. This has led to the creation of an extremely promising new generation of crystalline lasers that are both highly efficient and more reliable. The major part of this book is devoted to describing multilevel operating laser schemes for stimulated emission excitation in insulating crystals doped with lanthanide ions.The first part of Crystalline Lasers deals with the history of the physics and spectroscopy of insulating laser crystals. The chapters in the second part of the book present results from the study of Stark-energy levels of generating ions in laser crystals and their radiative and nonradiative intermanifold transition characteristics. This section includes extensive tabular data and reference information. Popular and novel operating schemes of crystalline lasers are covered in Part 3.In the chapters in the fourth part of the book, the newest technologies in the physics and engineering of crystalline lasers are considered. The results of investigations into laser action under selective excitations, miniature crystalline lasers, and the properties of nonlinear activated laser crystals are presented and analyzed.Crystalline Lasers summarizes and reviews the results of many years of research and studies of activator ions and multilevel operating laser schemes, and discusses exciting prospects of using these systems to create new types of crystalline lasers. This book will be of use to laser scientists and engineers, physicists, and chemical engineers.