We report on the first gas-source molecular beam epitaxy (GSMBE) growth of GaInAsP on GaAs substrates. The Hall mobility, X-ray diffraction and photoluminescence measurements indicate that high-quality GaInAsP and InGaAs/GaInAsP quantum wells were obtained. High-performance strained-layer InGaAs/GaInAsP/GaInP multiple-quantum-well lasers, emitting at 0.98 mum, have been demonstrated. A low threshold current density of 169 A/cm2 and a high characteristic temperature of 235 K were obtained for the laser with three quantum wells. A single mode CW room temperature operation was maintained up to 80 mW output power for an HR/AR coated 5.5 mum X 800 mum ridge waveguide laser. This study suggests that GSMBE is suitable for the growth of GaInAsP lattice matched to GaAs, and the GaInAsP is a promising candidate for optoelectronic device applications.