Quasi-phase-matched room-temperature frequency doubling to generate blue, green, and red light was demonstrated using periodically poled LiNbO3 crystals. A 1.24-mm-long sample in an external resonant cavity generated 1.7 W of green power from an input of 4.2 W at the 1.064-mu-m Nd:YAG laser line when heated to 140-degrees-C to compensate for a slight error in periodicity.