A comprehensive survey of recent theoretical and experimental progress in the area of electron-photon interaction and dense media. A state-of-the-art discussion of radiation production, with descriptions of new ideas and technologies that enhance the production of X-rays in the form of channelling, transition and parametric X-ray production. Progress in electron beam physics to produce sub-picosecond electron bunches from low-energy linear accelerators make it possible to produce coherent, high brightness, submillimeter radiation and sub-picosecond X-ray pulses. Micro-undulators in the form of bent crystalline structures hold great promise as future X-ray sources.Proceedings of the NATO Advanced Research Workshop, held in Nor-Hamberd, Yerevan, Armenia, June 25-29, 2001A comprehensive survey of recent theoretical and experimental progress in the area of electron-photon interaction and dense media. A state-of-the-art discussion of radiation production, with descriptions of new ideas and technologies that enhance the production of X-rays in the form of channelling, transition and parametric X-ray production. Progress in electron beam physics to produce sub-picosecond electron bunches from low-energy linear accelerators make it possible to produce coherent, high brightness, submillimeter radiation and sub-picosecond X-ray pulses. Micro-undulators in the form of bent crystalline structures hold great promise as future X-ray sources.Preface.1. Overview of Radiation from Dense Media; M.L. Ter-Mikayelyan.2. Channeling Radiation: A Historical Perspective; B. Berman.3. Parametric X-ray Radiation, Transition Radiation and Bremsstrahlung in X-Ray Region. A Comparative Analysis; A.P Potylitsyn, I.E. Vnukov.4. X-rays from Relativistic Electrons in Condensed Media; N.N. Nasonov.5. A Semiclassical Approach to the Radiation Damping Force; X. Artru, G. Bignon.6. Optical Transition and Diffraction Radiation Diagnostics for Relativistic Charged Particle Beams; R.B. Fiorito.7. Resonancló)