Laser flash photolysis (LFP) of 9-azidoanthracene produces singlet 9-anthrylnitrene ((1)AN) With lambda(max) = 331, 344. and 412 nm. The lifetime of (1)AN is 17 ns at 77 K and is 27 ns at ambient temperature and is controlled by intersystem crossing (ISC) to the lower energy triplet state. The rapid rate of ISC of (1)AN relative to singlet phenylnitrene is due to the small (5.3 kcal/mol, CASPT2 (14,14)) calculated singlet-triplet separation of the large delocalized nitrene. There is no evidence of cyclization of (1)AN to form a bridgehead azirine (AZ) species. This observation is in agreement with calculations that indicate that the conversion of (1)AN to AZ is endothermic by 23 kcal/mol.