The electrostatic polarization energies have been calculated for 17 molecular crystals, including some of two-components. Comparison with photoelectric emission data confirms that the energies of ionized states in organic crystals can be described in terms of properties of the free molecule and classical electrostatic interaction energies. The calculations were made in more detail and for a greater number of compounds than has been attempted previously; contributions from terms formerly neglected are significant especially for large molecules like pentacene.