In this talk, I will describe how recent advances in epitaxial growth have created new opportunities for integrating III-V optoelectronics on Si. Over the past several years, my group at Yale has been working to understand the growth of self-assembled quantum dots (SAQDs) and solar cells on GaP substrates; GaP itself has relatively few applications owing to its indirect bandgap and relatively low carrier mobilities. Recently, a handful of groups worldwide successfully demonstrated GaP on Si with very low defect density, and in 2012, 300 mm GaP on Si (GaP/Si) wafers became commercially available. We have recently transferred our expertise to these novel template materials, demonstrating the first visible LEDs using InGaAs SAQDs on Si and the highest open-circuit voltage GaAsP solar cells on GaP/Si. These two demonstrations show a novel pathway to Si-based light emitters and to low-cost, high-efficiency solar cells, respectively.