It is shown that 31P nuclear magnetic resonance (NMR) spectroscopy with magic angle spinning (MAS) discriminates among different types of PO 4 units occurring in borophosphate glasses. The isotropic 31P chemical shift of the PO 4 increases by nearly 70 ppm in going from the "branching unit," neutral and covalently bonded, to the "monomeric unit," which carries a -3 nominal charge. By using both stationary and MAS 31P spectra, we also obtain the average values, and distribution widths, for chemical shift anisotropy and the asymmetry factor of PO 4 units occurring in vitreous borophosphates. Analysis of these NMR spectra provides detailed information about the short-range order in these glasses. It is also shown that the 31P-NMR-MAS technique may contribute significantly to phase separation and crystallization studies of phosphorus-containing glasses.