Potential curves for all 62 valence states of C2 have been computed using configuration interaction wavefunctions within the valence orbital space. The valence orbitals were determined by a multiconfiguration self-consistent-field calculation using a properly dissociating set of configurations for the a 3Πu state. Comparison is made with the experimental spectroscopic constants for ten of these states: R e values are too large by ∼0.05 ao, the bond energies De are too small by ∼0.8 eV, Te values are within ∼0.34 eV, and ωe is generally within ∼70 cm -1. We have identified 19 other possible bound states not yet observed experimentally, and have obtained a good qualitative picture of the positions and shapes of the repulsive states which may be involved in dissociation processes. © 1979 American Institute of Physics.