Impacts on energetic materials may result in harmless fracture and dispersal or runaway violent reactions. The coupling between the mechanical stimulus and localized deformation plays an important role in determining how the material will respond. Energetic materials have complex microstructures with high densities of internal defects and interfaces. Furthermore, the energetic constituents are typically brittle, highly anisotropic molecular crystals. Simulations of the evolution of temperature and deformation in realistic microstructures will be reported that are based on new single crystal plasticity models for the energetic molecular crystals RDX and PETN. The single crystal plasticity models capture the volumetric response of the materials through free energy-based equations of state and the anisotropic elasticity of orthorhombic RDX and tetragonal PETN through tensors of single crystal elastic constants. High rate phenomenological and dislocation density-based anisotropic plasticity models have been developed for both materials using measurements of the elastic-plastic response of oriented single crystals under shock compression. The application of these models toward understanding and quantifying the mechanical responses of polycrystalline explosives, plastic bonded composites, and void collapse under high rate deformation will be presented.