The effect of core polarization on binding energies, term splitting, f
ine structure, and transition probabilities is investigated for the lo
w lying states 4s2S, 3d2D, 4p2P(o) in Ca II and 4s2(1)S, 4s4p1,3P(o) i
n Ca I. Results from inclusions of core polarization in the form of mo
del potentials are compared with explicit MCHF calculations, and the a
ccuracy of the different approaches is discussed.