Homophily—social grouping on the basis of similar traits—is a well-established intergroup dynamic. However, some evidence suggests that homophily emerges as a byproduct of people’s inferences about desirable qualities (e.g. trustworthiness, openness to experience) in others. In this set of hypotheses, we applied a social inference approach to studying how people formed groups on the basis of their attachment styles. More specifically, we hypothesized that people would affiliate with others who shared their degree of attachment avoidance, but would not affiliate with those who shared their degree of attachment anxiety. These hypotheses are consistent with evidence that avoidantly attached individuals—but not anxiously attached individuals—display qualities they find desirable in others. In a secondary exploration, we also tracked how far apart participants stood from each other as they waited for the study to start. We expected that this measure would mediate the relationship between individuals' attachment style and the attachment style of the groups they joined. However, since previous investigations have only linked attachment avoidance— but not anxiety—to interpersonal distance, we tentatively predicted that interpersonal distance would only mediate avoidance-based grouping.