In metal matrix composites, the spacing between discontinuous reinforcements can affect strengthening by interfering with the motion of dislocations through the metal.This project looks for similar phenomena in polymer matrix composites (PMCs), since the molecular activity of the polymer chains should be altered in the vicinity of the reinforcements.Awareness of such a trend can improve the understanding of PMC mechanics, which in turn can improve PMC characterization and selection techniques.This project sought a relationship between particle spacing and overall strengthening in a discontinuously-reinforced PMC test case composed of alumina particles in a polyphenylene sulfide matrix.Tensile tests were run on hot-pressed composite samples with varying reinforcement volume fraction and particle size.Data showed that composite strength increases as particle spacing increases, except at high volume fractions where this trend reverses.These results provide preliminary data but demonstrate a need for more in-depth investigation.