The structure of an aromatic polyamide, poly(p-phenylene-terephthalamide) (PPTA), was studied in the solid state using 15N nuclear magnetic resonance (NMR) spectroscopy. Spectra of uniaxially aligned molecules placed with the axis of alignment both parallel with and perpendicular to the applied magnetic field were analyzed to yield the orientations of specific molecular bonds with respect to the fiber axis. The 15N chemical shift tensor was characterized by simulating powder pattern spectra of both PPTA and a model compound, benzanilide. Chemical shift and dipolar coupled chemical shift line shapes were calculated through Euler angle transformations from the principal axis system (PAS) reference frame to the fiber axis system (FAS) frame. The orientations of NH and NC' bonds in PPTA are determined as well as the orientational distribution of the PPTA fiber axis. The structural parameters determined for PPTA are compared with those obtained by X-ray diffraction.