Since Hubble’s early classification of galaxies a century ago, it has been clear that galaxies fall into 2 broad categories – those that are blue and characterized by spiral disks, and those that are red and elliptical in shape. With the advent of modern spectroscopic surveys, this galaxy ‘bimodality’ has been understood in the context of star formation, in which galaxies can be broadly classified as either star forming or passive. However, the physical processes that regulate star formation, transforming galaxies between these populations, remain hotly debated. In this talk, I will review recent results that investigate some of the mechanisms proposed to play a role in the enhancement and suppression of star formation, including galaxy mergers, bars and the role of active galactic nuclei (AGN). I will also present new results from the SDSS MaNGA survey that uses spatially resolved spectroscopy to map where in the galaxy these processes are occurring. Taken together, I will show that whilst a wide variety of mechanisms can alter a galaxy’s global star formation, these processes seem to generally both boost and quench star formation from the inside-out.