Background: Research has seldom considered social capital at the individual, household and administrative area level simultaneously and examined its association with mental health.

Aim: The main purpose of this study was to examine the association between social capital and mental health while controlling for various confounders at multiple levels using multi-level analysis and operationalizing social capital at the individual, household and administrative area level.

Methods: This study used cross-sectional data from the 2010 Seoul Welfare Panel Study conducted by the Seoul Welfare Foundation (participation rates for the household and household members were 87.6% and 87.5%, respectively).

Results and conclusions: The main finding of this study was that organizational participation (B = 0.132, p < .001) and perceived helpfulness (B = 0.129, p < .001) were positively associated with mental health. This study also found that perceived helpfulness was positively associated with mental health (B = 0.070, p < .001). However, it did not find a significant association between the contextual level of social capital and mental health. The results indicate that the different dimensions of social capital may act differently to mental health depending on the level.