  We determine the age distribution of star clusters in the Antennae galaxies
(NGC 4038/9) for two mass-limited samples (M > 3 x 10^4 M_{\odot} and M > 2 x
10^5 M_{\odot}). This is based on integrated broadband UBVI and narrowband
H-alpha photometry from deep images taken with the Hubble Space Telescope. We
find that the age distribution of the clusters declines steeply, approximately
as dN/d\tau \propto \tau^{-1}. The median age of the clusters is ~10^7 yr,
which we interpret as evidence for rapid disruption ("infant mortality"). It is
very likely that most of the young clusters are not gravitationally bound and
were disrupted near the times they formed by the energy and momentum input from
young stars to the interstellar matter of the protoclusters. At least 20% and
possibly all stars form in clusters and/or associations, including those that
are unbound and short-lived.
