Supermassive black holes, and the active galactic nuclei (AGN) that they power, are thought to play an integral role in the evolution of galaxies by acting to regulate, and eventually quench, the star formation activity of their hosts. I will discuss recent efforts to test the AGN feedback scenario by studying the demographics of galaxies undergoing active black hole growth. In particular, I will highlight recent results from the CANDELS survey, which is using the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope to extend the detailed study of galaxy properties to z~2, the era when nuclear activity and star formation activity in the Universe are at their peak. I will discuss what CANDELS is currently revealing about the mechanisms that fuel AGN activity at z~2 and the connection between black hole growth and the emergence of the first generation of passive galaxies at this epoch.
