—A technique is devised for vapor-phase doping of CdS in the quaternary system Cd—In—Te—S. CdS crystals are doped with In and Te via four-zone annealing in Cd and InTe vapors. The luminescence spectra of the CdS〈In,Te〉[Cd] crystals (where [Cd] indicates annealing in cadmium vapor) are found to contain orange and red emission bands, in contrast to those of CdS[Cd] crystals, which are dominated by green emission. The CdS〈In,Te〉[Cd] crystals are shown to be photosensitive. Sphalerite (metastable) CdS crystals doped with In and Te are prepared under far-from-equilibrium conditions. The bands in their luminescence spectra are shifted to longer wavelengths as compared to stable CdS〈In,Te〉[Cd] crystals.