It is known that infectious diseases are able to influence the behavior of humans and other animals. Of particular interest is the phenomenon of “sickness behavior,” which has been well studied in animals. Briefly, sick animals exhibit organized changes across a variety of behaviors: they become anhedonic, exhibit depression and reduced food intake, and reduce their movement and exploratory behaviors, among other changes. Sickness behavior is thought to have evolved as a means of redirecting energy towards mounting a strong immune response to fight off the infection, at the expense of other activities. Compared to data from studies on animals, human sickness behavior is relatively unexplored. Vaccines have been used as a proxy for studying wild infections and immune activation in humans elsewhere in the literature. Our research seeks to expand upon this paradigm and examine changes in social behavior and mood, as well as hormonal correlates of these changes, following vaccination. This allows us to follow study participants from a known point of “infection” and more accurately map any changes of interest. Our research includes projects investigating both human social behaviors and parasite-mediated host behaviors.