A researcher trying to predict or interpret spectra oftransition metal ionsin possible laser host materials isconfronted with a variety of different methods of describingthe same physical situation. This book provides a systematicapproach to the applied theory of crystal-field interactionsof transition metal ions in 49 crystalline hosts that are orshow promise of being good laser materials.The tables that make up the main part of the book presentthe experimentally determined parameters of the 3dN, 4dN,and 5dN transition-metal ions in the second, third, andfourth ionization states. These parameters have beenconverted to Slater and crystal-field parameters.The book is a source for research workers in laserdevelopment and in crystal-field theory, and for graduatestudents of solid state chemistry and physics.