  Observations of Young Star Cluster ({\bf YSC}) systems in interacting
galaxies are reviewed with particular emphasis on their Luminosity Functions
({\bf LF}) and colour distributions. A few spectroscopic abundance measurements
are available. They will be compared to YSC abundance predictions from spiral
galaxy models. Evolutionary synthesis models allow to derive ages for
individual YSCs on the basis of their broad band colours. With individual YSC
ages, models predict the future colour and luminosity evolution of the YSC
systems that will be compared - after a Hubble time - to observations of old
Globular Cluster ({\bf GC}) systems. Using model M/L ratios as a function of
age, YSC masses can be estimated. Age spread effects in young systems can cause
the shape of the LF to substantially differ from the shape of the underlying
mass function. Major sources of uncertainty are the metallicity, dust
reddening, and observational colour uncertainties.
