  We present SLUG, a new code to "Stochastically Light Up Galaxies". SLUG
populates star clusters by randomly drawing stars from an initial mass function
(IMF) and then following their time evolution with stellar models and an
observationally-motivated prescription for cluster disruption. For a choice of
star formation history, metallicity, and IMF, SLUG outputs synthetic photometry
for clusters and field stars with a proper treatment of stochastic star
formation. SLUG generates realistic distributions of star clusters,
demonstrating the range of properties that result from finite sampling of an
IMF and a random distribution of ages. The simulated data sets provide a
quantitative means to address open problems in studies of star formation in
galaxies and clusters, such as a test for IMF variations that are suggested by
the systematic deficiency in the H-alpha/UV ratio in outer disks or in dwarf
galaxies. SLUG will be made publicly available through the website
http://sites.google.com/site/runslug/.
