Abstract: A multi-compatible sizing composition that includes an epoxy resin emulsion, a silane coupling agent package, a non-ionic lubricant, and a crystalline polyol is provided. The epoxy resin desirably has an epoxy equivalent weight from 180-195. A preferred emulsifier is a modified polyethylene oxide-polypropylene oxide block copolymer. The silane coupling agent package includes an aminosilane and a vinyl silane coupling agent. The sizing composition may be used equally well with epoxy, unsaturated polyester, and vinylester thermosetting resins. Reinforcement fibers sized with the inventive sizing composition possess low friction on contact points, low fuzz, and reduced drag. Other performance characteristics such as in-plane shear and dynamic fatigue are also improved by the multi-compatible sizing composition. Fibers sized with the multi-compatible sizing composition may be used, for example, to form woven rovings and fabrics, in filament winding applications, and in pultrusion processes.