Abstract: Over the last several years, there has been growing consensus in the theoretical literature about the process of galaxy growth through cold gas accretion. Both analytic calculations and numerical simulations suggest that high-redshift galaxies primarily grow by smoothly accreting cold gas from the surrounding intergalactic medium (IGM). Furthermore, simulations indicate that gas is accreted in collimated cool streams containing both smooth gas and small galaxies. While recent theoretical work has identified the importance of cold accretion, spectroscopic observations have much more consistently indicated the existence of large-scale outflows from star-forming galaxies at high redshift. Resolving the apparent disconnect between simulations and observations and identifying observational signatures of infalling gas are crucial for testing the theoretical paradigm of cold accretion. Here we present new evidence for the smoking gun of cool gas accreting onto star-forming galaxies at high redshift (z~1-3), using spectroscopy of both HI and heavy elements. We also describe new insights into the properties of outflowing gas around galaxies, which will provide important constraints on models for star-formation feedback.