Sexual selection shapes mating habits, morphologies, and behaviors in a multitude of species. However, few sexually selected morphological traits have been documented in the highly social insects (ants, termites, bees, and wasps). And, though cases of mating plugs and male-male competition have been described, the limited evidence for some forms of sexual selection in social insects has led to the hypothesis that sexual selection has not played as large a role in the social Hymenoptera as in other taxa because social taxa may be constrained by the opposing pressure of kin selection (Boomsma, 2007). In particular, it has been suggested that the monandrous breeding systems of many social insect species allow few opportunities for sexual selection beyond basic forms of assortative mating (Boomsma, 2007; Hughes et al., 2008). I sought to test this hypothesis by performing a multi-year series of studies examining sexual selection in social insects. The findings suggest that sexual selection, particularly male mate choice, may play an important role in social insect mating systems and their evolution. I hypothesize that social insect males, due to their physiology and life histories, should practice mate choice. Male mate choice is likely to evolve in systems in which males invest valuable or limited resources during mating, and there is high variation in female quality. For many social insects these conditions hold. Most social insect males undergo spermatogenesis during a single period of development and therefore have a limited number of sperm to invest in their lifetime. Males may therefore be “choosy” about their sperm allocation decisions. Additionally, females vary significantly in their ability to survive overwintering (hibernation) and to successfully establish a colony. Short-lived social insect males can only realize reproductive success by mating with females that are able to survive long enough to produce reproductive offspring. Therefore, we can hypothesize that males will preferentially mate with females that display characteristics associated with survival and fecundity, such as larger size. To test the prediction that male mate choice is occurring in the highly social wasp Vespula maculifrons, I first determined which female traits were associated with mating success, a key component to reproductive fitness. Female length was significantly associated with mating success in all three study years, though in opposing directions. In two of the three years, longer females mated more frequently than shorter females, while in one year shorter females enjoyed greater mating success. These findings suggest that female length may play an important role in V. maculifrons mating behavior and led us to test whether female length was associated with female longevity. A link between female length and reproductive fitness (i.e. mating and survival) would be consistent with the hypothesis that males are choosing to mate with high quality females. Therefore, I tested what morphological and genetic factors influenced female overwintering survival and whether female mating status was associated with longer survival during hibernation. My findings were in line with the prediction that female length, because of its association with mating success, would also be significantly associated with overwintering longevity. This suggests that longer females are better able to survive overwintering and that males, in two of the study years, mated at higher frequencies with longer, more fit females. Interestingly, we also found that females sired by particular males mated at significantly higher than expected frequencies, though paternity was not found to affect survival or physical length. Though we cannot rule out other potential influences such as female quality, these findings are consistent with male mate choice not being based only on traits associated with female longevity; males may also be using multiple cues to determine other traits associated with female fitness such as fecundity. Overall, this work represents an integrated and comprehensive study of mate choice and sexual selection in social insects and suggests that social insects are not exempt from some forms of sexual selection as some theories posit.