  Our knowledge about unresolved stellar systems comes from comparing
integrated-light properties to SSP models. Therefore it is crucial to calibrate
the latter as well as possible by integrated-light colors of clusters that have
reliable ages and metallicities (deep CMDs and/or spectroscopy of individual
giants). This is especially true for the NIR and MIR, which contain important
population synthesis diagnostics and are often used to derive masses of stellar
systems at hight redshifts. Here we present integrated colors of MC clusters
using new VRI photometry and 2MASS data. In the imminent future we will include
MIR data from Spitzer/IRAC. We compare our new colors with popular SSP models
to illustrate their strengths and weaknesses.
