This paper presents the main results of a high-resolution 150 MHz C-13 NMR characterization of polypropene samples prepared in the presence of a number of last-generation Ziegler-Natta catalyst systems. The configurational analysis of the polymers, in particular, was expanded from the pentad level (normally afforded by routine spectra) to the nonad level. This proved to be beneficial in mechanistic studies on the origin of the stereospecificity.