This book has grown out of our shared experience in the development of the Stanford Synchrotron Radiation Laboratory (SSRL), based on the electron-positron storage ring SPEAR at the Stanford Linear Accelerator Center (SLAC) starting in Summer, 1973. The immense potential of the photon beam from SPEAR became obvious as soon as experiments using the beam started to run in May, 1974. The rapid growth of interest in using the beam since that time and the growth of other facilities using high-energy storage rings (see Chapters 1 and 3) demonstrates how the users of this source of radiation are finding applications in an increasingly wide variety of fields of science and technology. In assembling the list of authors for this book, we have tried to cover as many of the applications of synchrotron radiation, both realized already or in the process of realization, as we can. Inevitably, there are omissions both through lack of space and because many projects are at an early stage. We thank the authors for their efforts and cooperation in producing what we believe is the most comprehensive treatment of synchrotron radiation research to date.