Equilibrium geometries and electronic properties of neutral Cun (n = 2, 3, 4, 6, 8, 10) clusters are determined via first principles calculations which treat s and d electrons on an equal footing. Overall, we find ground state and local minimum structures similar to those of Nan. However, Cun clusters tend to prefer more compact arrangements. Electronic states with atomic s-character are strongly hybridized with d-states and located mostly at the band edges. Angular decomposition of the electronic wavefunctions in Cun clusters shows that their shell model character is significantly less pronounced than in Nan clusters.