Abstract: What is the nature of Dark Energy? What is the physical mechanism that seeded the formation of structure in the Universe? What is the mass of neutrinos? These fundamental questions can be addressed by analyzing the clustering of galaxies and I will explain how using examples of measurements made using the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). I will describe the efforts that I have led to maximize the robustness of BOSS results and the methods that can be developed to maximize the precision of the future results. I will then describe The Dark Energy Survey (DES), the work I have done for it so far, and how the methods I developed in my previous studies (BOSS and otherwise) are being and will be extended and applied to the analysis of DES data. I conclude with a brief discussion of the opportunities that will be afforded by the Large Synoptic Survey Telescope (LSST).