Several isomers of C72− were studied with electron correlation methods and augmented, correlation-consistent basis sets. All are thermodynamically stable with respect to dissociation into C5− and C2− anions. Isomerization energies are less than 5 kcal/mol at the highest level of theory. Vertical and adiabatic electron detachment energies are positive for the D3h form of C72−. Linear, carbene, bridged-chain, and chain-ring isomers are considered as well. Feynman–Dyson amplitudes connecting dianionic and anionic states reveal extensive delocalization of the least bound electrons.