The Lawrence Berkeley and Lawrence Livermore National Laboratories will host a workshop on Xenon-based detectors on 16 -18 November 2009 at LBNL, Berkeley, California. The goal of the workshop is to explore the status, prospects, and issues for xenon-based detectors, primarily for direct detection of WIMPs and neutrino-less double beta decay. The workshop will bring together researchers engaged in current and possible next-generation detectors based on xenon, in liquid or gas phase, as well as experts in argon- and neon-based detectors. The workshop scope includes fundamental energy transfer processes, signal formation, technical advances, and detector performance. An overall aim is to provide a true workshop setting to encourage full and frank discussion, not only of technical progress and emerging ideas, but also of enduring challenges for which adequate solutions are needed.