I am a NSF Astronomy and Astrophysics Fellow at the Harvard-Smithsonian Center for Astrophysics. I use observations of resolved stellar populations to constrain stellar evolution models. My focus is on phases that have the greatest impact on galaxies but that we understand the least. So far, that's been the luminous core helium fusing phase (contained within the blue or red supergiant phase), asymptotic giant branch (AGB) stars, and stars that have failed to become AGB stars.