The stability of anionic aluminum-nitrogen clusters has been examined and Al2N-, Al3N2-, Al5N2-, Al6N3-, Al8N3-, and Al9N2-are found to be particularly stable. Theoretical density functional calculations on neutral and anionic AlnN (n=1-8) clusters were performed and the stability and reaction energetics with oxygen examined. Clusters requiring less than 5.7 eV to remove an electron and an Al atom are shown to be resistant to the reaction with oxygen.