Intellectual humility involves awareness of the limitations of one’s knowledge and that one’s beliefs might be incorrect. Despite documented prosocial and cognitive benefits of intellectual humility, few studies have examined factors that support long-term changes in intellectual humility. The current study investigated whether affiliative interactions with a new conversation partner were associated with changes in intellectual humility over time. Participants (N = 937) completed four weekly guided conversations with an initially-unacquainted peer and reported on their relationship after each conversation. Participants also reported their intellectual humility prior to the first conversation, immediately after the last conversation, and one month following the last conversation. As hypothesized, perceiving greater affiliation with one’s conversation partner was associated with greater increases in intellectual humility over time. These findings suggest a potential intervention for increasing intellectual humility and demonstrate that interpersonal factors are linked to open mindedness and awareness of the limitations of one’s knowledge.