  Semi-analytical models of galaxy formation based on hierarchical clustering
now make a wide range of predictions for observable properties of galaxies at
low and high redshift. This article concentrates on 2 aspects: (1)
Self-consistent modelling of dust absorption predicts a mean UV extinction
A_{UV} ~ 1 mag, depending only weakly on redshift, and similar to observational
estimates. (2) The models predict that the Lyman-break galaxies found at z ~ 3
should be strongly clustered with a comoving correlation length r_0 = 4-7 Mpc/h
(depending on the cosmology), in good agreement with subsequent observational
determinations.
