We describe and demonstrate a process for ZnSe epitaxial lateral overgrowth (ELOG) on stripe-patterned, oxide-masked (1 1 1)GaAs substrates using a simple near-equilibrium chemical Vapor transport process based on a reversible reaction mediated by hydrogen at atmospheric pressure. The ELOG process exhibits excellent selectivity, wherein epitaxial seeding and initial growth is restricted to mask openings, and subsequent lateral epitaxy has aspect ratios as high as 20. We also achieved near-seamless impinging growth of continuous epilayers of ZnSe on the masked substrate. Etch-pit density studies indicate defect reduction in areas of the ZnSe overgrown atop the oxide compared to areas of the ZnSe epilayer seeded directly over the mask openings. The composite GaAs substrate, oxide mask, and ZnSe epilayer structure is under considerable stress due to the thermal expansion mismatch of these materials. Some approaches for reducing thermal stress are discussed.