The properties of a number of states of calcium are determined from a large basis configuration interaction calculation. The main focus is on the polarizabilities of the low lying states (the 4s2 1Se, 4s3d 1,3De, 4s4p 1,3Po, and 4s5s 1,3Se states) and the dispersion interactions of those states with the calcium ground state, the hydrogen atom, and the rare gases.