A survey of the jet-cooled (NbC)-C-12 and (NbC)-C-13 radicals has been carried out between 13 500 and 18 000 cm(-1) using laser-induced fluorescence and resonant two-photon ionization spectroscopy. Several vibronic bands belonging to at least six band systems have been identified. Three of these systems appear to belong to (2) Pi(1/2)-(2) Delta(3/2) transitions in which the lower (2) Delta(3/2) stateis the ground electronic state of the molecule. The other three systems also terminate to the same three (2) Pi(1/2) upper states? but originate from a state lying 830 cm(-1) above the X (2) Delta(3/2) state. This state is assigned as the A (2) Sigma(+) state. The ionization potential has been determined to be 56402+/-15 cm(-1) or 6.9929+/-0.0018 eV using two-color photoionization efficiency spectroscopy. This value, combined with the ionization potential of Nb and the bond energy of NbC+, yields an improved bond energy of 5.39+/-0.15 eV for NbC. The (4,0) band of the B (2) Pi(1/2)-X (2) Delta(3/2) system has been studied at a resolution of approximately 0.005 cm(-1) using laser-induced fluorescence spectroscopy. The nuclear magnetic hyperfine structure has been resolved in both states, and an analysis confirms that the (2) Delta ground state arises from the sigma(2) delta(1) electron configuration in which the unpaired delta electron is a pure Yb 4d electron associated with the F-4 term arising from the excited 5s(2)4d(3) electron configuration. Density functional calculations have been carried out on the lowest (2) Delta, (2) Sigma(+), (4) Delta, (2) Pi, and (4)(Pi,Phi) states of the neutral and the (1) Sigma(+), (3) Delta, and 3(Pi,Phi) states of the cations. These calculations fully support the experimental evidence for the ground state.