Climate-interior coupled evolution is investigated for Venus by merging a partial-melting/parameterized mantle convection model with a gray radiative-convective atmospheric model. A positive feedback process can operate by the release of water to the atmosphere via mantle melting, leading to an increase in atmospheric opacity and the radiative temperature gradient. The resulting amplification of the greenhouse surface temperature raises the mantle temperature leading to an increase in the partial-melting rate. Using thin-lid convection, a coupled model for Venus running over an interval of 3 to 1 Ga shows a significant increase in surface temperature, partial-melting extent, and extrusive magma flux compared to a model where there is no communication between greenhouse-modulated surface temperature and partial-melting in the interior. Coupled and uncoupled models that transition (with variable timing) to stagnant-lid convection either shut down partial melting via lithospheric thickening, or evolve to large amounts of melt due to increased interior temperatures. ¿ 2001 American Geophysical Union