Discontinuously reinforced aluminum (DRA) composites have been processed to contain discrete regions of unreinforced aluminum with the objective of enhancing the damage tolerance. The effects of changes in the ductile phase size, shape and strength as well as the SiCp reinforcement distribution on the toughness were studied. The incorporation of the ductile phase can increase the crack growth resistance of the DRA composite. In such cases, stable crack propagation (i.e. R curve behavior) is observed in contrast to the behavior of the conventional DRA composite which fails catastrophically under the conditions tested. The level of toughening is affected by the size and mechanical properties of the ductile phase as well as the orientation and shape of the ductile regions with respect to the test geometry (i.e. crack arrestor vs crack divider).