Large-scale CI calculations are carried out to obtain accurate bending potential energy curves for the 1 A 1 and 2 B 1 components of the A Π u electronic state of NCN and the electric transition moment functions for the A Π u - X Σ g spectral system of this molecule. These data are combined to compute the vibronic structure in the A Π u state and the intensity distribution within the A Π u - X Σ g band system. The calculations reproduce reliably the results of recent measurements of the 000-000 and 010-010 transitions in the A Π u - X Σ g system by laser excitation spectroscopy [S. A. Beaton, Y. Ito, and J. M. Brown, J. Mol. Spectrosc. 178, 99-107 (1996); S. A. Beaton and J. M. Brown, J. Mol. Spectrosc. 183, 347-359 (1997)] and predict positions and intensities for yet unobserved bands of the same system.