Intellectual humility involves awareness that one’s knowledge has limitations and that one’s beliefs might be incorrect. Despite documented benefits of intellectual humility, few studies have examined factors associated with long-term changes in intellectual humility. This study investigated whether an intervention focused on guided conversations was associated with increases in intellectual humility and whether these changes were stronger when people perceived greater affiliation with their conversation partner. Participants (N = 937) completed an intervention with four guided conversations and reported on their relationship with their partner after each conversation. Intellectual humility was measured before the first conversation, immediately after the last conversation, and 1 month following the last conversation. As hypothesized, intellectual humility increased over time, especially when people perceived greater affiliation with their conversation partner. These findings suggest that intellectual humility interventions with social components may have stronger effects when people pereive greater affiliation with their partners.