  The problem of the formation and evolution of field massive galaxies is
briefly reviewed from an observational perspective. The motivations and the
characteristics of the K20 survey are outlined. The redshift distribution of
Ks<20 galaxies, the evolution of the rest-frame Ks-band luminosity function and
luminosity density to z=1.5, the nature and the role of the red galaxy
population are presented. Such results are compared with the predictions of
models of galaxy evolution.
