Three-component systems with a polypropylene (PP) matrix consisting of polar elastomer (ethylene-propylene rubber and styrene-ethylene-butylene-styrene grafted with maleic anhydride) or of polar PP (PP grafted with maleic anhydride) and filler were investigated. Three microstructures of PP-elastomer-filler hybrids were obtained by processing control and elastomer or PP modification with the maleic anhydride : fillers and rubber particles were separated in the PP matrix, rubber particles with filler core were distributed in the PP matrix, and mixed microstructures of the first and second. A study of mechanical properties showed that the elastic modulus increased in the first microstructure and impact strength increased in the second microstructure. Mechanisms for the relationships between microstructure, processing, and mechanical properties are discussed.