Compositions comprising (i) a crystalline, isotactic propylene homopolymer, (ii) an ethylene/.alpha.-olefin elastomeric impact modifier, and (iii) a reinforcing grade of filler, for example, talc. The crystalline isotactic propylene homopolymer has a flex modulus of greater than about 1930 MPa and a heat deflection temperature (HDT) of greater than about 100.degree. C.; the ethylene/.alpha.-olefin interpolymer has a Tg of less than about -30.degree. C., and a tan delta measured at 0.1 radians/s at 190.degree. C. of less than about 2; and the filler has a HDT reinforcing efficiency of at least about 2. The composition has an HDT of greater than about 100.degree. C. and a flex modulus of greater than about 1930 MPa.