Abstract:A substantial body of research, based largely on North American and European contexts, demonstrates that social networks play a critical role in protecting and promoting mental, as well as physical, health. The purpose of this study is to examine how "weak" and "strong" network relations are differentially related to individual mental health (depressive symptoms) based on a nationally representative sample of South Korean adults. Using multilevel analysis, the current research also investigates the extent to which contextual or neighborhood-level factors moderate the associations between depression and social network. Findings show that regular interaction with weaker ties (acquaintances, neighbors, coworkers, etc.) are associated with better mental health. The number of strong ties (family members and friends), on the other hand, is not a significant predictor of psychological distress. In addition, a cross-level interaction term is observed: The negative relationship between weak ties and depressive symptoms is diminished in neighborhoods with more foreign-born residents or immigrants. General implications beyond the empirical case under investigation are discussed, as to why weak ties can be "strong" in relation to mental health and how this phenomenon can vary according to residential characteristics such as ethnic heterogeneity.