Constraints on Galaxy Formation from the Tully-Fisher Relation

New models for the formation of disk galaxies are presented. I discuss the contraints on galaxy formation that follow from fitting the model to the near-infrared Tully-Fisher (TF) relation, with an emphasis on reproducing the small amount of scatter observed. Once the parameters that describe the supernova feedback are tuned to fit the slope of the observed TF relation, the model reproduces the correct amount of TF scatter, and yields gas mass fractions, mass-to-light ratios, and characteristic accelerations that are all in excellent agreement with observations.