Simultaneous mode‐locking and quasi cw second‐harmonic generation (SHG) in high‐temperature lithium niobate or barium sodium niobate of a Nd3+:YAG laser have been accomplished by electro‐optic modulation of the nonlinear medium. This technique will be useful for obtaining ``100% conversion efficiencies,'' which would not be possible by the standard intracavity method, with nonlinear crystals that are either too short or have too low a nonlinear coefficient to achieve optimum coupling of the laser.