This study investigates the influence of Lewis number on radiative extinction and flamelet modeling. The interaction of Lewis number with different transient effects, such as fluctuating reactant concentrations, fluctuating reactant temperatures, and variable partial premixing, are considered. The results underscore the importance of including the effect of non-unity Lewis numbers and their interaction with chemistry and unsteadiness in improving the predictive capability of flamelet combustion modeling approach, and in precise determination of radiation-induced extinction limits. An increase of Lewis pushes the radiation-induced extinction limit, which occurs at low strain rates, toward higher values of strain rates.