Observations of molecular gas in distant galaxies are experiencing a coming-of-age, transitioning from a “discovery” to a “survey” mode.  New and upgraded facilities are now making it possible to survey molecular gas efficiently in large galaxy samples, and these observations are proving to be critical in refining our general picture of galaxy evolution.  In this talk, I will review recent results from the two largest surveys for molecular gas in normal star-forming galaxies, the z=0 IRAM-30m COLD GASS survey and the z=1-2 IRAM-PdBI PHIBSS survey, and show how they combine to lend strong support in favor of the “equilibrium” model for galaxy evolution, under which most of galaxy evolution is regulated by gas supply and the efficiency of the star formation process.