These proceedings collect the papers presented at the Eighth International Conference on Synchrotron Radiation Instrumentation, held in San Francisco, August 25th to 29th 2003. This conference takes place every three years, hosted by synchrotron research centers around the world. It is the principal meeting for developers of synchrotron radiation techniques. This particular meeting hosted 650 delegates and there are about 350 published papers in the proceedings. This proceedings series is an essential reference work for practitioners of the field. It documents the evolution and development of techniques. Many of the ideas that become standard practice in synchrotron radiation research appear first in these volumes, often with the definitive explanation and rationale for the technique in question.