Spectroscopic ellipsometry (SE) and quartz crystal microbalance with dissipation monitoring (QCM-D) have become popular tools for the analysis of organic films, from a few Angstroms to a few micrometers in thickness, at the solid-liquid interface. Because of their different working principles, both techniques are highly complementary, providing insight into optical and mechanical properties, respectively. The combination of SE and QCM-D in one setup is not only attractive because this information becomes available at the same time on the same sample, but also because the correlation of SE and QCM-D responses can provide novel insight that is not accessible with either technique alone. Here, we discuss how the combined setup is implemented in practice and review current data analysis approaches that are useful with regard to the correlation of both methods. Particular attention is given to the novel insight that can be obtained by the combination of both techniques, such as the solvation, density and lateral organization of organic films.