Van der Giessen and Needleman present a discrete dislocation plasticity model for small-strain plasticity problems, where plastic flow is represented by the collective motion of discrete dislocations. Dislocations are modeled as line defects in a linear elastic medium. The solution is obtained by superposition of the infinite-medium solution for the dislocations and a complementary solution that enforces boundary conditions. The model incorporates lattice resistance, dislocation nucleation, and annihilation through constitutive rules. Plane-strain boundary value problems are solved for solids with edge dislocations on parallel slip planes. Monophase and composite materials under simple shear are analyzed. The results show a peak in the shear stress versus shear strain curve, followed by a plateau associated with localized dislocation activity. The model is compared with continuum slip descriptions of plastic flow. The formulation accounts for discrete dislocation effects through a boundary value problem approach. The model is applied to two-dimensional plane strain problems, with results demonstrating the influence of dislocation sources, obstacles, and nucleation on plastic deformation. The results for composite materials are compared with continuum-based plasticity theories. The model is validated through simulations of dislocation dynamics and continuum plasticity, showing the importance of dislocation interactions in plastic deformation.Van der Giessen and Needleman present a discrete dislocation plasticity model for small-strain plasticity problems, where plastic flow is represented by the collective motion of discrete dislocations. Dislocations are modeled as line defects in a linear elastic medium. The solution is obtained by superposition of the infinite-medium solution for the dislocations and a complementary solution that enforces boundary conditions. The model incorporates lattice resistance, dislocation nucleation, and annihilation through constitutive rules. Plane-strain boundary value problems are solved for solids with edge dislocations on parallel slip planes. Monophase and composite materials under simple shear are analyzed. The results show a peak in the shear stress versus shear strain curve, followed by a plateau associated with localized dislocation activity. The model is compared with continuum slip descriptions of plastic flow. The formulation accounts for discrete dislocation effects through a boundary value problem approach. The model is applied to two-dimensional plane strain problems, with results demonstrating the influence of dislocation sources, obstacles, and nucleation on plastic deformation. The results for composite materials are compared with continuum-based plasticity theories. The model is validated through simulations of dislocation dynamics and continuum plasticity, showing the importance of dislocation interactions in plastic deformation.