We provide a brief overview of the proposed structure of CMIP6 to encourage discussion and feedback that willb e considered in refining the design.  As an initiative of the World Clmate Research Programme (WCRP), the Climate Model Intercomparison Project (CMIP) is meant to provide open access to baseline information about model behavior and performance and focus on three broad science questions:  How does the Earth system respond to forcing?  What are the origins and consequences of systematic model biases?  How can we assess future climate changes given climate variability, climate predictability, and uncertainties in scenarios?