  We investigate the correlation of star formation quenching with internal
galaxy properties and large scale environment (halo mass) in empirical data and
theoretical models. We make use of the halo-based Group Catalog of Yang and
collaborators, which is based on the Sloan Digital Sky Survey. Data from the
Galaxy Evolution Explorer (GALEX) are also used to extract the recent star
formation rate. In order to investigate the environmental effects, we examine
the properties of "central" and "satellite" galaxies separately. For central
galaxies, we are unable to conclude whether star formation quenching is
primarily connected with halo mass or stellar mass, because these two
quantities are themselves strongly correlated. For satellite galaxies, a nearly
equally strong dependence on halo mass and stellar mass is seen. We make the
same comparison for five different semi-analytic models based on three
independently developed codes. We find that the models with AGN feedback
reproduce reasonably well the dependence of the fraction of central red and
passive galaxies on halo mass and stellar mass. However, for satellite
galaxies, the same models badly overproduce the fraction of red/passive
galaxies and do not reproduce the empirical trends with stellar mass or halo
mass. This {\em satellite overquenching problem} is caused by the too-rapid
stripping of the satellites' hot gas halos, which leads to rapid strangulation
of star formation.
