This study was conducted to understand food acquisition practices from social networks and its relationship with household food security. In-depth interviews and a survey on food security were conducted with twenty-nine mothers and one father in metropolitan areas of South Korea. Many families acquired food from their extended families, mainly participants' mothers. Between low-income and non-low-income households, there was a pattern of more active sharing of food through private networks among non-low-income households. Most of the low-income households received food support from public social networks, such as government and charity institutions. Despite the assistance, most of them perceived food insecurity. We hypothesized that the lack of private social support may exacerbate the food security status of low-income households, despite formal food assistance from government and social welfare institutions. Interviews revealed that certain food items were perceived as lacking, such as animal-based protein sources and fresh produce, which are relatively expensive in this setting. Future programs should consider what would alleviate food insecurity among low-income households and determine the right instruments and mode of resolving the unmet needs. Future research could evaluate the quantitative relationship between private resources and food insecurity in households with various income statuses.