A review is given of the current status of the polarization magneto-optics of crystals with paramagnetic impurity ions. Methods for measuring the magnetic circular anisotropy are discussed and a review is given of the results obtained in recent years by traditional magneto-optic investigations (including the magnetooptic activity in the absorption spectra of intrinsic and impurity defects in crystals, magnetic circular polarization of the luminescence, and anisotropy of the magneto-optic activity in cubic crystals). Attention is concentrated on new methods in polarization magneto-optics, which include investigations of the interaction of the spin system with the crystal lattice, particularly the spin-lattice relaxation and spin memory effects, experiments on radio-optic double resonance, investigations of the optical spin relaxation, nonlinear magneto-optic effects, etc.