We describe weak lensing measurements of galaxy halos. Early SDSS data are used to measure the galaxy-mass correlation function (GMCF). This GMCF is a direct measure of the massive halos which luminous galaxies occupy. To make these measurements we use a sample of ~35,000 lens galaxies and 3.6×106 background 'source' galaxies. Every lens galaxy has a spectroscopic redshift and highly accurate five color photometry. As a result our determination of the mass and size scales of the GMCF are very robust. Detailed information about all lens objects also allows us to study the relationship between the luminous properties of galaxies (luminosity, morphology, local density) and the dark matter halos which surround them. To make this comparison we define an aperture mass M260, which characterizes the normalization of the GMCF. While M260 is essentially independent of the u′ luminosity of a galaxy, we find that it is linearly dependent on luminosity in red bands. This suggests that the current rate of star formation in a galaxy (reflected by the u′ light) is poorly correlated with its dark matter environment. The light in redder bands however, which reflects the integrated star formation history of the lenses, is closely coupled to the dark matter halos in which the galaxies form.
