People who are in close relationships tend to do and like the same things, a phenomenon termed the "homophily principle." The present research probed for evidence of the homophily principle in 4- to 6-year-old children. Across two experiments, participants (N = 327; 166 girls, 161 boys; located in the Midwestern United States) were asked to predict the closeness of two people based on their preferences. Participants in Experiment 1 indicated that people with a shared preference or a shared dispreference were more closely affiliated than people whose preferences diverged, suggesting inferences of homophily. Furthermore, children were not only relying on the emotional valences expressed: They expected people with a shared preference to be closer than people who expressed positive emotions about different items and expected people with a shared dispreference to be closer than people who expressed negative emotions about different items. Experiment 2 replicated and extended the main findings of Experiment 1 with more naturalistic stimuli. The present studies provide strong evidence that young children apply the homophily principle to their reasoning about social relationships.