An understanding of the work hardening behavior of particulate reinforced metal-matrix composites is crucial in optimizing the parameters for deformation processing of these materials. The microstructure and mechanical properties of these composites can be altered by a suitable aging treatment. The precipitation hardening mechanisms can be changed by moving from an underaged to an overaged microstructure. In particulate reinforced composites, however, the strength and ductility, as measured by strain to fracture, are determined predominantly by the effects of the reinforcement. Thus, a model for predicting the mechanical properties of particulate reinforced composites should be able to do so for all aging conditions. In this paper a modified continuum model is used to relate the work hardening behavior of the composite to microstructural parameters. The model is also used to predict the fracture strain of the composite for an underaged and an overaged condition. The model is shown to predict the fracture strain of the composite quite accurately for both aging conditions.