Preface. Part I: Introduction. 1. Distance Measurements by CW and Pulsed EPR; S.S. Eaton, G.R. Eaton. 2. Relaxation Times of Organic Radicals and Transition Metal Ions; S.S. Eaton, G.R. Eaton. Part II: CW Measurements. 3. Structural Information from CW-EPR Spectra of Dipolar Coupled Nitroxide Spin Labels; E.J. Hustedt, A.H. Beth. 4. Determination of Protein Folds and Conformational Dynamics using Spin-Labeling EPR Spectroscopy; H.S. Mchaourab, E. Perozo. 5. EPR Spectroscopic Ruler: the Deconvolution Method and its Applications; Wenzhong Xiao, Yeon-Kyun Shin. 6. TOAC: The Rigid Nitroxide Side Chain; J.C. McNulty, G.L. Millhauser. 7. Depth of Immersion of Paramagnetic Centers in Biological Systems; G.I. Likhtenshtein. Part III: Pulsed EPR Measurements of Electron-Electron Interactions. 8. Determination of Distances Based on T1 and Tm Effects; S.S. Eaton, G.R. Eaton. 9. Double-Quantum ESR and Distance Measurements; P.P. Borbat, J.H. Freed. 10. `2+1' Pulse Sequence as Applied for Distance and Spatial Distribution Measurements of Paramagnetic Centers; A. Raitsimring. 11. Double Electron-Electron Resonance; G. Jeschke, et al. Part IV: Applications to Photosynthesis. 12. Electron Paramagnetic Resonance Distance Measurements in Photosynthetic Reaction Centers; K.V. Lakshmi, G.W. Brudvig. 13. Photo-Induced Radical Pairs Investigated using Out-of-Phase Electron Spin Echo; S.A. Dzuba, A.J. Hoff.