Chemical communication is the most widespread form of communication, present in all multicellular organisms, yet its diversity is poorly understood. In this dissertation, I investigated male chemical signaling in fringe-lipped bats (Trachops cirrhosus). First, I described a novel odorous crust on the forearm of male fringe-lipped bats. I found that the forearm crust coincides with the expression of an enlarged chest gland and enlarged testes. In addition, using long-term capture data I found that the prevalence of males with forearm crust increased during the putative female reproductive season. Together, these findings suggest that the forearm crust plays a role in female mate choice or male-male competition. I also tested the response of adult females and adult males with forearm crust to the odor of males with and without forearm crust. Contrary to my prediction, I found strong evidence that males with forearm crusts avoid other males with forearm crust. Unlike the few studies that have investigated the role of odorous traits in other bat species, my results suggest that the chemical compounds in the forearm crust could mediate male-male interactions rather than those between males and females. Finally, to elucidate the role that social structure can play on male behavior, I characterized the group composition and associations among fringe-lipped bats. I found that females have preferred roosting partners despite often switching roosts. Furthermore, relatedness predicted association rates among females but not for males. Characterizing the social structure and group dynamics of fringe-lipped bats can inform broader patterns and the causes and consequences of the evolution of sociality.