Configuration interaction calculations of the 3Π and 1Π states arising from N(1s) ionization of NO are described. The inclusion of orbital relaxation effects leads to improved agreement with the experimental multiplet splitting and intensity ratio compared to the frozen orbital approximation. However, calculated correlation effects lead to an increased multiplet splitting and to poorer agreement with the experimental intensity ratio. Predictions are made concerning the “shake-up” peaks which should be observed associated with N(1s) ionization.