Laser‐driven semiconductor photoemitters can provide the very bright beams of electrons needed in advanced accelerators. However, these semiconductors are easily degraded in operation. Photoemissive testing of the compound LaB6, which is expected to be a more environmentally rugged material, has shown that under excimer laser irradiation normalized electron beam brightnesses of 6.7×106, 2.6×106, and 1.5×105A/cm2 rad2can be achieved at photon wavelengths, respectively, of 193, 248, and 308 nm.