Multidimensional Fourier Transform Spectroscopic techniques originated in NMR, where they proved very powerful for disentangling complex spectra and elucidating interactions among resonances. Recently, there has been great interest in extending these techniques into the infrared and visible spectral regions. We have developed methods to do so based on active interferometric stabilization to achieve the required phase coherence. We have applied this technique to the study of excitonic resonances in semiconductor quantum wells. Unique insight gained into the microscopic many-body interactions that dominate the nonlinear optical response. By manipulating the polarization of the incident optical pulses, signatures of two-exciton states can be isolated.