Background: This study aimed to examine the association between size and intimacy of social networks and substantial depressive symptoms, and further, to assess the moderating roles of age diversity and age difference in these linkages, in the community-dwelling adult population in South Korea.Methods: A South Korean population of 2,363 in the Cardiovascular and Metabolic Disease Etiology Research Center cohort was utilized. Each participant’s social network characteristics were measured using the egocentric social network analysis tool. Substantial depressive symptoms were assessed using the Beck Depression Inventory-II (BDI-II). Multivariable logistic regression was used to compute odds ratios (ORs) for substantial depressive symptoms by different social network characteristics.Results: Mean perceived intimacy of social networks had an inverse association with substantial depressive symptoms; Overall, the size of social networks had a negative association with depressive symptoms. In women, age diversity and age difference had moderation effects on the association of network size and intimacy with substantial depressive symptoms. The association of network size and intimacy with substantial depressive symptoms was stronger than women’s average (OR=3.23; 95% CI=1.91-5.47) when social networks had a higher age diversity (OR=4.95; 2.32-10.51) and higher age differences (OR=5.38; 2.22-13.05).Limitations: Substantial Depressive symptoms were measured according to self-assessed levels of depressive symptoms during the previous two weeks, which do not necessarily indicate depressive disorder. Categorization of certain variables was made considering the distribution, but not with the actual critical known cut-off.Conclusions: We found that low social network size and intimacy were linearly associated with substantial depressive symptoms in women. Women whose networks are small-sized, less intimate, and with high age diversity and age difference, especially with older persons are more likely to have depressive symptoms in South Korean settings.Trial registration: KCT0001038, Clinical Research Information Service (CRIS)