2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/12158The evolution of QSO clustering is investigated with a new sample of 388 QSOs with 0.3<z<2.2, B<20.5 and M_B<-23. Evidence is found for an increase of the clustering amplitude with increasing redshift. These measurements allow to further distinguish among the various physical scenarios proposed to interpret the QSO phenomenon. A single population model is inconsistent with the observations. The general properties of the QSO population would arise naturally if quasars are short-lived events connected to a characteristic halo mass ~5x10^{12} M_sun.4 pages, 2 figures, LaTex, uses lamuphys.sty. Contributed talk at ESO/ATNF Workshop ``Looking Deep in the Southern Sky'', Sydney, Australia, 10--12 December 1997, eds. R. Morganti and W. CouchAstrophysicstext