The microscale deformation of an Al-Mg alloy with a bimodal grain size distribution, consisting of coarse grains (CGs) and ultrafine grains (UFGs) is studied through finite element methods. Procedurally generated models are created to characterize the behavior of this microstructure at different scales. The mechanical response of individual grains is represented through crystal plasticity laws, which include accommodations for solute and grain size strengthening effects. These effects are quantified through multiscale models allowing for experimental calibration. Additionally, the behavior of grain boundaries is included through cohesive interface models. Using these techniques, grain scale deformation is characterized, load distribution between the two phases is examined, and the roles of crystal anisotropy and interface accommodation are considered.