Book excerpt: This volume provides a detailed examination of the physical basis for EPR imaging and in vivo EPR spectroscopy, experimental arrangements, and data analysis. The EPR imaging methods described include continuous wave, spin-echo-detected and ENDOR-detected EPR with constant, stepped, modulated, and pulsed magnetic field gradients. Applications described include inhomogeneous materials, diffusion kinetics, reaction kinetics, orientation of liquid crystals, microwave distributions, magnetic field distributions, superconductors, radiation damage, and defects in solids. The book also covers other topics important to in vivo studies, including in vivo EPR spectroscopy, low-frequency EPR, state-of-the-art low-frequency EPR instruments, achievable sensitivity, and spin labels. The book will be of great interest to graduate students, researchers, and medical instrument developers who use EPR, as well as clinicians and chemists interested in the relationship between in vivo radicals (such as superoxide and diseases).