The redshift range z=1-2 corresponds to the era when the star formation density of the Universe peaked, and the time when most of the stars in today’s massive galaxies were formed.  Galaxies at these early times were drastically different from those locally, with massive, gas-rich galaxies undergoing rapid star formation in globally unstable disks, and the Hubble sequence not yet in place.  In this talk, I will review some of the recent observations which measure the interaction between star formation and gas dynamics within the ISM of hundreds of high-redshift galaxies on scales that range from a few kilo-parsecs to just 100’s of parsecs.  The goal of the observations is to constrain how the star formation assembled the bulk of the stellar mass in today’s massive galaxies and how secular processes crystallised the Hubble sequence around z~1.