An elemental abundance analysis of Vega has been performed using high-signal-to-noise 2.4 Å mm-1 Reticon observations of the region λλ4313-4809. Vega is found to be a metal-poor star with a mean under-abundance of 0.60 dex. The He/H ratio of 0.03 as derived from He I λ4472 suggests that the superficial helium convection zone has disappeared and that radiative diffusion is producing the photospheric abundance anomalies.