We report the 13C NMR spectra of amorphous hydrogenated carbon and boron carbide. The amorphous hydrogenated carbon spectra consist primarily of a sp2 carbon peak at 40 ppm and a sp3 carbon peak at 140 ppm and are in reasonable agreement with recent theoretical calculations of Mauri, Pfrommer, and Louie, but there are some noteable discrepancies. The amorphous hydrogenated boron carbide spectra are very different from that of amorphous hydrogenated carbon, showing two sharp lines at 135 and 170 ppm at low boron concentrations and an intense, broader line at 15 ppm at high boron concentrations. We suggest the two sharp lines at 135 and 170 ppm could be due to carbon atoms in boron-containing aromatic rings, and the broader line at 15 ppm as due to carbon atoms in boron carbide icosahedra. These lines provide evidence of nanocrystalline structure imbedded in an amorphous hydrogenated boron carbide matrix.