Coherent visible light, continuously tunable over the range from 4200 to 7300 Å, has been obtained by pumping an ammonium dihydrogen phosphate (ADP) crystal with the ultraviolet fourth harmonic of a Nd: YAG laser. Parametric gains sufficient to produce up to 25% average power conversion of the pump to the tunable visible output were obtained without the use of an external resonator. The output radiation typically had a 5‐Å bandwidth, 2‐nsec pulse duration, 100‐kW peak power, and 5‐mW average power at 30 pps. Wavelength tuning was accomplished either by varying the crystal temperature, or by varying its orientation with respect to the pump beam. Angle tuning allows the output to be rapidly tuned across the visible spectrum.