Discussions at the Ninth Annual Meeting of the GEWEX Hydrometeorology Panel (GHP) in September 2003 led to establishment of a Transferability Working Group (TWG) to advance the science of regional climate modeling and to take advantage of coordinated continental-scale observations and analyses. The mission of the TWG is to understand physical processes underpinning the global water and energy cycles and their predictability through systematic intercomparisons of regional climate simulations on several continents and comparison of these simulated climates with coordinated continental-scale observations and analyses. In this talk, we present an overview of motivations and goals and some initial results of transferability experiments. Experiments promoted by this group will address updated GEWEX science questions relating to feedbacks and natural variability, acceleration of the water cycle, seasonal to interannual predictability, and impacts on water resources. Through these experiments, TWG is in essence asking, "How portable are our models?" and "How general is our understanding of the physics underlying our models?" TWG will provide a means for systematic evaluation of simulations of different climatic regions by “meta-comparison” of individual and ensemble performance among domains as well as on particular domains. Anchored by coordinated observations from continental scale experiments, modeling studies under TWG will examine influences of parameterization choices, resolution and nesting dependencies, boundary influences, and internal model variability on the quality of predictions. TWG will solicit interest among regional modeling groups for these experiments and will coordinate with other related regional climate model intercomparisons. The emphasis of the transferability experiments is to apply several models on several domains or single models on multiple domains as opposed to multiple models on single domains. Regional model intercomparisons already completed and ongoing (PIRCS, PRUDENCE, RMIP, etc.) provide a framework for analysis of the water and energy cycle components produced by multiple models on multiple domains. This paper will provide an overview of lessons learned and future opportunities for applications of transferability.