Regional climate models (RCMs) are widely used tools to produce high resolution climate simulations at regional scales. The ICTP regional climate modeling system, RegCM, is one of the most used RCMs worldwide, with applications ranging from regional process studies to paleoclimate, climate change, chemistry-climate and biosphere-atmosphere interactions. A new version of the model, RegCM4, has been completed and released in 2012, but new features are being included for release during this workshop, such as the CLM4.5 land surface scheme, a new cloud microphysics scheme and coupling with the MIT Ocean model. As in previous workshops of this series, this event will provide lectures and extensive hands-on sessions on the theory of regional climate change and regional climate modeling as well as on the use of the RegCM4 modeling system. The focus of the present workshop will be on the application of the RegCM4 within the international program CORDEX (COordinated Regional Downscaling EXperiment. The primary aim of CORDEX is to produce a new generation of large multi-model ensembles of regional climate change projections over domains covering all continental areas of the world for use in impact assessment and adaptation studies. The RegCM community contributes to CORDEX through the completion of numerical experiments over different CORDEX domains. The workshop is thus intended to provide a forum to assess and intercompare these experiments within the context of the goals of CORDEX. The workshop is also aimed at providing a forum for current and future model users to discuss relevant issues and formulate needs and priorities for further model development and dissemination. A limited number of participants is envisioned, with proven experience in climate modeling and a strong interest in using the RegCM4 system for regional climate studies.