Abstract: Intraspecific social interactions, which often determine individual fitness, are the driving forces of sexual and social selection.  One way to quantify social relationships and relate them to evolutionary processes is with social network theory.  Several reviewers have suggested that social networks may be able to predict fitness, but this theory has not been tested.  This study investigated the fitness correlates of social networks in a wild population of forked fungus beetles (Bolitotherus cornutus).  Information about beetle interactions was collected from multiple scans per night over the sampling period.  The component of fitness used was mating success, defined as mate guards and attempted copulations seen from the scans and video cameras set up for behavioral observations.  Social networks were created in UCINET social network software, where interactions were unweighted and defined as any times two beetles came within five centimeters of each other.  The separate male and female networks were measured using three biologically relevant social network metrics: degree, closeness, and clustering coefficient.  A generalized linear model included these three measures and elytra length as parameters, with fitness as the dependent variable.  In males, closeness positively correlated with fitness and clustering coefficient negatively correlated with fitness, while degree did not correlate.  We explain this result with a hypothesis that beetles with high fitness move frequently between brackets, interacting with a few individuals on each bracket.  Social network measures did not predict female fitness; however, elytra length was positively correlated with fitness.  This study shows that social networks may be important predictors of fitness and that they may be valuable tools in the study of evolutionary processes such as social and sexual selection.