This volume contains the proceedings of the Workshop on Physics with an Electron-Polarized Ion Collider (EPIC-99), jointly sponsored by the Indiana University Cyclotron Facility and Nuclear Theory Center, and the Institute for Nuclear Theory, University of Washington. It was held in Bloomington, Indiana, April 8-11, 1999. The purpose was to discuss important new physics phenomena which could be investigated with a high-luminosity asymmetric collider consisting of a beam of polarized electrons (with energy roughly 5 GeV), and a beam of polarized protons or other light ions of approximately 40...