The formation, transport and segregation of components in nuclear fuels fundamentally control their behavior, performance, longevity and safety. Most nuclear fuels enter service with a uniform composition consisting of a single phase with two or three components. Fission products form introducing more components. The segregation and transport of the components is complicated by the underlying microstructure consisting of grains, pores, bubbles and more, which is evolving during service. As they evolve, components and microstructural features interact such that composition affects microstructure and vice versa. The ability to predict compositional and microstructural evolution in 3D as a function of burn-up would greatly improve the ability to design safe, high burn-up nuclear fuels. We present a model that combines elements of Potts Monte Carlo, MC, and the phase-field model to treat coupled microstructural- compositional evolution. The evolution process demonstrated is grain growth and diffusion in a two-phase system. The hybrid model uses an equation of state, EOS, based on the microstructural state and composition. The microstructural portion uses the traditional MC EOS and the compositional portion uses the phase-field EOS: (Formula Presented) Ev is the bulk free energy of each site i and J is the neighbor interaction energy between neighboring sites i and j. The last term is the compositional interfacial energy as defined in the traditional phase-field model. The coupled microstructure-composition fields evolve by minimizing the free energy in a path dependent manner. An application of this modeling framework demonstrates the expected microstructural and phase coarsening, which is controlled by long-range diffusion.