We have observed, for the first time to our knowledge, stimulated emission in atomic-copper vapor that is excited by a resonant tunable laser beam. One of the important and interesting results obtained in this experiment is that excitation of the (2)P(1/2) level of the copper atoms generates strong amplified spontaneous emission (ASE) for both(2)P(1/2)-(2)D(3/2) and (2)P(3/2)-(2)D(5/2) transitions. This is the first reported direct experimental evidence observed for collisional mixing between the (2)P(1/2) and (2)P(3/2) levels in a copper-vapor laser. Excitation of the (2)P(3/2) level induces substantially weaker ASE for the (2)P(1/2)-(2)D(3/2) transition. In addition, we observed collision-induced ASE for both transitions over a wide range of detuning of the pump frequency. The preliminary results of the experiment are presented, and the implications of the results for high-pressure copper-vapor lasers are discussed.