Electron beam excitation of CdS crystals grown in an atmosphere of excess Cd has resulted in laser emission near 4900 A˚ with 350 W of peak output power and 26.5% overall (35% internal) power efficiency at temperatures as high as 110°K. Laser action was observed, although at considerably reduced levels of power and efficiency, at temperatures up to 250°K. The high performance of the lasers appears to be due to increased crystal uniformity and to the introduction or enhancement of highly efficient radiative transitions, both of which result from the Cd‐rich growth conditions.