Using mainly CASSCF/cc-pVTZ ab initio methods we have computed the ground X 3 Ω - and several excited states of the NLi species. In particular, we calculated full potential energy curves of the X 3 Ω - , 5 Ω - (dissociative), A 3 , a 1 Δ, b 1 Ω + , B 3 Ω - , c 1 , C 3 and d 1 states. For six of these states the molecular constants ω e , ω e χ e , α e and D e have also been obtained. For the ground X 3 Ω - state a dissociation energy D e = 29.5 kcal mol - 1 has been calculated at the MR-CISD level.