In this study, aging characteristics of an aluminum-based metallic matrix reinforced with two different sizes of silicon carbide were investigated. The results showed similar aging kinetics in the case of unreinforced samples and composite samples containing coarser (34.4 mu m) SiC particulates and accelerated aging kinetics in the case of composite samples containing finer (8 mu m) SiC particulates. Results of microstructural characterization studies show that composite samples containing finer SiC particulates exhibited finer grain size, lower porosity, reduced cluster-to-particulate-size ratio, and superior interfacial integrity. The accelerated aging kinetics exhibited by composite samples containing a distribution of finer SiC particulates, when compared to the unreinforced and reinforced samples containing a distribution of coarser SiC particulates, were rationalized in terms of their microstructural characteristics.