  In the first part of this article, we review observations of the mass and
luminosity functions of young and old star cluster systems. We also review some
of the physical processes that may determine the characteristic mass of
globular clusters and the form of their mass function. In the second part of
this article, we summarize our models for the disruption of clusters and the
corresponding evolution of the mass function. Much of our focus here is on
understanding why the mass function of globular clusters has no more than a
weak dependence on radius within their host galaxies.
