The lowest-lying X-1 Sigma(+), a(3)Phi, b(3)Pi, c(5)Delta, A(1)Phi, and B-1 Pi electronic states of CoN have been investigated at the ab initio MRCI and MS-CASPT2 levels, with extended atomic basis sets and inclusion of scalar relativistic effects. Among the singlet states, the A(1)Phi and B-1 Pi states have been described for the first time. Potential energy curves, excitation energies, spectroscopic constants, and bonding character for all states are reported. Comparison with other early transition-metal nitrides (ScN, TiN, VN, and CrN), isoelectronic (NiC) and isovalent (RhN and IrN) species has been made, besides analyzing the B-1 Pi <-> X-1 Sigma(+) electronic transition in terms of Franck-Condon factors, Einstein coefficients, and radiative lifetimes. At both levels of theory, the following energetic order has been obtained: X-1 Sigma(+), a(3)Phi, b(3)Pi, c(5)Delta, A(1)Phi, and B-1 Pi, with good agreement with experimental results. In contrast, previous DFT and MRCI calculations predicted the ground state to be the (5)Delta state.