Multiconfipuration ( M C ) S C F calculations are reported for COz for bond angles bctween 60" and 180'. The ground state configuration is found to be.. .5af46:lb:laf for small bending angles and.. -6 a~3 b j l b~l a~ for large bending angles, the change in ground state character occurring at a bond angle of about 1 0 0 O . The force constant for bending obtained from the MC-SCF function is about 8.0% lower than the corrcsponding S C F value, and in considerably better agreement with experiment.