Observational Constraints on the Primordial Helium Abundance

Abstract

I will review recent progress on the observational determination of the primordial helium abundance (Yp). Presently, the best constraints on Yp come from observations of star forming regions in very metal-poor galaxies (although the impact of Yp on the CMB has been detected). Progress has come through the discovery of more very metal-poor galaxies and by extending spectral observations in to the near infrared with, for example, the Large Binocular Telescope.