Metallicity Studies in the IR: Unveiling Obscured Clusters of Our Galaxy

We review direct and indirect methods to derive metallicity through infrared spectroscopy of massive stars. The choice of different spectral types to obtain abundances allows to trace metallicity for a wide range of ages of the cluster hosting the massive stars. These methods have a great potential to understand the evolution of large amount of heavily obscured galactic clusters, which are currently being discovered through infrared surveys.