The effects of processing variables on the mechanical behavior and the void content of one-part epoxy based glass fabric composites produced by resin transfer molding (RTM) were investigated. The variables studied included injection pressure, injection temperature, and fabric structure. Image analysis was used to measure the void content in the composites. Variations in injection pressure and temperature were found to have a significant effect on the quality and the mechanical performance of composites. The optimized physical and mechanical performance of the composites was obtained by processing the resin at 160°C under 392 kPa pressure. Molding of highly permeable EF420 fabric required a shorter mold filling time, but resulted in reduced flexural strength and storage modulus in the resulting composites as compared with that of the composites containing 1581 fabric.