The technique of gravitational lensing, when combined with sensitive multiwavelength observations, provides a direct probe of mass distributions in galaxies without requiring that the mass be luminous. This is especially important for galaxies beyond our local Universe, for which traditional dynamical mass estimates are difficult or impossible to obtain with current instrumentation. I will discuss work in progress on measuring the properties of moderate redshift galaxies, from the large-scale halos to the substructures predicted by dark matter simulations.