The properties of commercial and experimental small particle dental composite formulations and selected unfilled resins have been evaluated in a systematic way. The unfilled resins were evaluated for percent conversion, molar heat of cure and microhardness as a function of resin composition, and ambient temperature of cure. The results show that the ambient temperature and resin composition may significantly influence these properties. Moderately higher ambient temperature of cure in the range 40 to 60°C and proper resin selection was found to significantly improve the resin properties studied. The diametral tensile strength, top hardness, bottom hardness, thermal expansion (TE) coefficient, watersorption (WS), and average surface roughness of composite resins were also evaluated as a function of filler particle size (PS) and volume fraction (VF) in a series of experimental composites and in selected commercial systems. The results show a dominant contribution of filler VF to all the composite properties and additional significant PS and VF-PS interactive effects in some composite properties.