Book excerpt: We developed here fundamental models of plasticity, based on dislocation dynamics and atomistic computer simulation methods for the prediction of the strength and plastic deformation at the nano-to-micro-length scales. The models are applied to the simulation of plastic flow in ultra-strong nano-laminates. The developed methods are: (1) An ab-initio based hybrid approach based on an extension of the parametric dislocation dynamics (DD) to bi-materials where the dislocation spreading over the interface is explicitly accounted; (2) a hybrid ab initio-discrete dislocation dynamics model to study the core structure in straight and curved dislocations, with application to single layers and across material interfaces; (3) Molecular dynamics (MD) modeling of dislocation motion and deformation in nano-layered composite materials and twins; and (4) Dislocation Dynamics (DD) modeling of dislocation motion and deformation modes of anisotropic, nano-layered composite materials.