Garth Illingworth, Rychard Bouwens and the HUDF09 Team The recent extraordinarily deep WFC3/IR data from the HUDF09 program has dramatically expanded our insights to the galaxy population at z~7-8-9. In particular, as part of our program of identifying and characterizing the galaxy population at high redshift (z>~4) we have been undertaking a thorough analysis of the rest-frame continuum slopes as a function of luminosity to much lower luminosities than previous studies. We have used very deep fields (the HUDF, HUDF09 and the HUDF05 datasets), as well as extremely faint objects from highly magnified sources from cluster lensing surveys to derive the contribution from lower luminosity galaxies to as faint as 0.03-0.06L* from redshift 2-7. We have noted a significant changes in UV slopes, aided by the new WFC3/IR data, over the redshift range z~3-7, probably due to changing dust extinction. We have incorporated recent results on the contribution of ULIRGS and sub-mm star-forming galaxies to indicate that in the first 2 Gyr the dominant contributors to the star formation rate density in the universe are the lower luminosity, and likely lower mass objects, that are fully represented in the Lyman Break population at z~4-7. Evidence from the HST WFC3/IR and Spitzer IRAC data over the HUDF suggests that we are probably beginning to see a population of low luminosity galaxies with very low metallicities at z~7. I will contrast the striking evolution from z~7-8-9 to z~2-3-4, including the stellar population characteristics and the results from recent structural analyses.