Data are presented demonstrating room-temperature operation of Al xGa1-xAs-GaAs vertical-cavity surface-emitting lasers grown on Si substrates. The device structures are grown using molecular beam epitaxy and a grown-in quarter-wave AlAs-GaAs stack is used as the n-side reflector and a nonalloyed Ag dot used as the p-side reflector/contact. Pulsed threshold currents of ∼125 mA are obtained for a 15-μm-diam device.