This paper is a critical review of the available phase equilibria, crystallographic, and thermodynamic data for the vanadium-nitrogen system. Three nitride phases have been identified and their crystal structures, ranges of homogeneity, and melting or decomposition temperatures determined. The solvus boundary for the vanadium-rich solid solution is placed at 3.8 At. pct n at 550 deg. C and increases to 11 at. pct n at 1,500 deg c. A break in the solvus observed at 550 deg c is associated with the formation of a metastable phase, v16n. Other metastable phases have been identified, but their exact stoichiometries and structures have not been unambiguously determined. The enthalpies and free energies of formation, heat capacities, and dissociation pressures for the subnitride and mononitride were evaluated and correlated.