The tensile strength of a discontinuous composite system consisting of aligned, unidirectional prepreg platelets is predicted by performing progressive damage analyses in a periodic representative volume element. Interlaminar and in-plane damage mechanisms are combined to yield failure characteristics of the meso-structure. The length-to-thickness ratio of the platelet was found to be the primary variable for control of system strength and failure mode. A critical platelet aspect ratio was determined as that ratio wherein system strength is maximized. Further, composite strength variability was shown to be vary inversely with aspect ratio, while attaining a minimum at the critical aspect ratio.