The field and temperature dependencies of free carrier photogeneration efficiencies of vapor deposited molecular glasses have been studied by time-of-flight photocurrent techniques, The measured photogeneration efficiencies were analyzed by a theory of geminate recombination due to Onsager. In spite of the wide distribution of the charge mobilities and molecular dipole moments of the materials studied, thermalization distances and primary quantum yields were 27-36 Angstrom and 10(-3) to 10(-2), respectively. The results suggest that the thermalization process in molecular glasses is not driven by processes that determine bulk transport properties.