Electron Momentum Spectroscopy (EMS) is a powerful “orbital imaging” technique, which enables direct experimental reconstructions of one-electron transition momentum densities associated to specific ionization channels. In this talk, we will illustrate for a number of cases treated by our group over the last 10 years how a proper analysis of EMS experiments gives insight in momentum space onto the consequences of electron correlation (configuration interactions) and nuclear dynamics in the initial (neutral) and final (ionized) state onto the shape (spread and topology) of molecular orbitals.