Contents: 1. Data Sources. Extent of the Literature. Textbooks and Monographs. Literature Reviews. Data Tabulations. Societies and Conferences. Conventions and Notation. Physical Constants and Conversion Factors. 2. Computer Techniques. Spectrometer Control and Data Sampling. Data Processing and Analysis. Spectrum Simulation. Line -Shape Analysis. Hamiltonian Fitting. Literature Searches. 3. Relaxation, Background, and Theory. Relaxation Time Constants. Bloch Equations. Chemical Exchange. Relaxation in Diluted Solids. Relaxation in Liquids. Relaxation in Concentrated Systems. Experimental Techniques. 4. Relaxation Data Tabulation. Transition Metal Ions. Solvated Electrons and Inorganic Radicals. Organic Radicals. Motional Effects. Exchange. 5. ENDOR Spectroscopy. ENDOR Fundamentals. ENDOR in Liquid Phase. ENDOR in the Solid-State. Pulsed ENDOR. 6. ENDOR Data Tabulations. Data for: 1H and 2H, 13C, 14N and 15N, 19F, 25Mg, 27Al, 29Si, 31P, 117Sn and 119Sn, 203Tl and 205Tl, Alkali Nuclei. Radicals Trapped in Crystals, Matrices, and Solutions. Triplet-State Radicals. Free Radicals in Biological Systems. Inorganic Radicals and Ions. Defects and Complexes on Surfaces. Impurity Centers in Semiconductors.