The morphology and properties of high modulus polypropylenes (PP) are characterized over a wide range of material variables. These variables include the tacticity, room temperature xylene solubles (XSRT), molecular weight, melt flow rate (MFR), and polydispersity index (PI). Flexural modulus in quench-cooled compression moldings of propylene homopolymer can be correlated to the volume fraction crystallinity, phic, by an empirical logarithmic dependence. The quantitative zero orientation results for the quench-cooled compression moldings provide an approximate crystallinity normalization for oriented moldings. WAXS analyses of crystalline orientation were determined over a range of melt temperatures and mold locations and correlated to the skin area fraction by optical microscopy. WAXS analysis of the balance of orientations for the crystallographic axes suggest that the orientation balance is primarily determined by the "melt orientability" of the resin type. An empirical description of flexural modulus in injection molded PP is developed for the range of material variables and molding conditions studied. This description is represented as a function of crystallinity-normalized modulus vs. the frozen-in crystalline orientation.