  We summarize our detailed, physically grounded, model for the early
co-evolution of spheroidal galaxies and of active nuclei at their centers
(astro-ph/0307202). Our predictions are excellent agreement with observations
for a number of observables which proved to be extremely challenging for all
the current semi-analytic models, including the sub-mm counts and the
corresponding redshift distributions, and the epoch-dependent K-band luminosity
function of spheroidal galaxies. Also, the black hole mass function and the
relationship between the black hole mass and the velocity dispersion in the
galaxy are nicely reproduced.
