A user-material subroutine has been written to incorporate single crystal plasticity in the

fmite element program ABAQUS. The fmite-element formulation of elastic-plastic and viscoplastic

single crystal deformation is reviewed in this paper. including versions for small deformation

theory and for the rigorous theory of finite-strain and fmite-rotation. Inelastic deformation of a

single crystal arises from crystalline slip, which is assumed here to obey the Schmid law. Various

self and latent hardening relations between resolved shear stress and shear strain in slip systems are

presented and incorporated as options in the subroutine.