Energy transfer has been observed between trivalent chromium and ytterbium ions in a silicate glass. Optical absorption and emission spectra of Cr3+and Yb3+are presented and show that the chromium emission, which occurs as a broad‐band fluorescence in the near‐infrared, overlaps the ytterbium absorption. Hence Cr3+ions can be used to sensitize YB3+fluorescence. Cr3+‐to‐Yb3+energy transfer was established from the Yb3+fluorescence excitation spectrum and the decrease in the Cr3+fluorescence intensity and lifetime. A decrease in the Yb3+lifetime with increasing Cr3+content was also observed indicating relaxation of Yb3+by back transfer to the faster relaxing Cr3+ions. Measurements of the Yb3+and Cr3+fluorescence lifetimes as a function of temperature and chromium content are reported.