Sulfide glasses of 50GaS3/2∙20GeS2∙20LaS3/2∙10LnSn/2 (Ln=rare earth ions, n=2 for Eu and 3 for other ions) compositions have been prepared. The wavelength dispersions in the Faraday effect of the glasses have been examined. Glasses containing LaS3/2 and YS3/2 have positive Verdet constants in the wavelength region from 550 to 850 nm, and the magnitude of the Verdet constants decreases with increasing wavelength. On the other hand, the Verdet constants of glasses containing Eu2+ and Ce3+ are negative, and the absolute magnitude of the Verdet constants decreases with increasing wavelength. The effective transition wavelengths of glasses containing various paramagnetic rare‐earth ions have been calculated based on the Van Vleck and Hebb theory. Factors determining the Verdet constants of these glasses are discussed. © 1996 American Institute of Physics.