  I will show that photometry -- if extending over a reasonable choice of
passbands -- can give fairly precise information about young star clusters and
their evolutionary state. Optical colors alone are known to leave severe
ambiguities due to degeneracies between age, metallicity and extinction. High
quality photometry including $U, B, V$ or $I$, and a NIR band, however, in
combination with an extensive grid of evolutionary synthesis models for star
clusters and a dedicated tool to analyse spectral energy distributions allows
to assess and largely disentangle star cluster ages, metallicities, extinction
values and, hence, to derive their masses. Gaseous emission contributions
sensibly affect broad band colors during the youngest stages, depending on
metallicity. Mass functions of young star cluster systems may considerably
differ in shape from luminosity functions. An ESO ASTROVIRTEL project provides
multi-color photometry for a large number of young, intermediate age and old
star cluster systems. As a first example I show results obtained for NGC 1569.
