<p>Research on neighborhoods demonstrates that where you live shapes many life outcomes. Yet evidence on the mechanisms of these neighborhood effects is less prevalent. Scholars theorize that social interactions are one primary mechanism, especially interactions between different social groups, and this idea undergirds urban policies promoting social mix. In this paper, we investigate whether neighborhood characteristics, especially the level of income mixing, correlate to levels of individuals’ social interactions. We use a large-scale household survey in Hong Kong because of the city’s rare urban context. It is highly segregated by income, but its high-density built environment is more homogenous than most cities. Using a multilevel mixed-effects ordered logistic regression, we find that people in more socially homogeneous neighborhoods do not interact with their neighbors more or less than those in more mixed neighborhoods. In spite of the city’s relatively homogenous built environment, the type of residential built environment does affect neighborly interaction, however, as do individual characteristics such as age and education.</p>