Need for cognitive closure predicts preference for similar others and reduced diversity in social networks.

People vary in their tolerance for uncertainty, and this motivation—known as Need for Cognitive Closure (NFC)—can shape social behavior. Individuals high in NFC are driven to avoid ambiguity and quickly resolve uncertainty. Because interacting with similar others (homophily) tends to reduce uncertainty, while engaging with dissimilar others (heterophily) can increase it, we examined whether NFC predicts preferences for homophilous over heterophilous interactions. Across four correlational studies and a preregistered experiment, we found that higher NFC was consistently associated with lower heterophily. Meta-analytic results confirmed the robustness of this association across samples. High-NFC individuals also reported fewer acquaintances and fewer people to discuss important matters with. To investigate whether uncertainty reduction motivates these patterns, we experimentally induced uncertainty and assessed participants’ social preferences. As predicted, uncertainty reduced interest in interacting with dissimilar others, especially among individuals high in NFC. These findings suggest that a fundamental motivation to reduce uncertainty influences the diversity and composition of people’s social networks. This has broader implications for social support, the construction of shared realities, and the persistence of group-based stereotypes.