  We examine the relation between galaxy properties and environment in the SDSS
DR2, quantifying environment in terms of the mass of the host halo, which is
obtained with a new iterative group finder. We find that galaxy type fractions
scale strongly and smoothly with halo mass, but, at fixed mass, not with
luminosity. We compare these findings with the semi-analytical galaxy formation
model of Croton et al. (2006). The discrepancies we find can be explained with
an oversimplified implementation of strangulation, the neglect of tidal
stripping, and shortcomings in the treatments of dust extinction and/or AGN
feedback.
