Recent investigations into the charge generation efficiency in bulk-heterojunction organic photovoltaic systems have highlighted the importance of both the static spatial separation of the electron-hole pair that occurs during an excitonic transition (quantified by the ground-to-exciton difference dipole moment ∆µ) and the associated excess polarization volume of the exciton (quantified by the ground-to-exciton difference polarizability tensor ∆p). We use Stark spectroscopy to experimentally measure the dipole change (∆µ) and polarizability change (∆p) accompanied by the ground to excited state electronic transitions in polymer and fullerene systems relevant for organic photovoltaic (OPV) applications. We compare our results to those calculated from theory for the excitonic transitions.