  The distribution of black hole masses in galaxies is constrained by
photometric and kinematic studies of individual galaxies, and by the properties
of the quasar population. I review our understanding of these topics, present
new results of adiabatic black hole growth models for HST photometry of
elliptical galaxies with brightness profiles of the `core' type, and discuss
the implications of ground-based stellar kinematical data. It is not yet
possible to uniquely determine the black hole mass distribution, but the
available evidence is not inconsistent with a picture in which: (i) a majority
of galaxies has black holes; (ii) there is a correlation (with large scatter)
between black holes mass M_BH and spheroid luminosity L_sph, approximately of
the form M_BH = 10^{-2} L_sph (in solar B-band units); and (iii) the black
holes formed in a quasar phase through mass accretion with an efficiency of
approximately 0.05.
