There is robust evidence of the health-enhancing benefits of social relationships and support, especially for inflammatory processes. Most research is limited to adults. In children and adolescents, the social support literature focuses on individual sources of support (i.e., mother). An encompassing, comprehensive measure of support spanning a child’s entire social network may help to unify findings across developmental areas. The thesis aims were twofold: Part 1 explored a novel multidimensional conceptualization of social support named “social hygge”, and Part 2 tested the relation between social hygge and chronic low-grade inflammation in children and adolescents. Data from the population-based Quebec Child and Adolescent Health and Social (QCAHS) survey were analyzed. Youth aged 9, 13, and 16 years (N = 3613) and their parents answered questions about their social relationships and support. A subsample (n = 2204) provided a fasting blood draw that was assayed for C-reactive protein (CRP). Part 1 explored the psychometrics of three quantitative approaches: traditional, data-driven, and social hygge to derive principal components. Part 2 tested the relation between these derived components with CRP, adjusting for age, sex, body mass index and smoking. All multidimensional social hygge scores were associated with lower CRP in adolescents (η2p = .003-.005); no association was found for children. Effect sizes were comparable to those previously reported in adults. Findings support a possible latent construct that more broadly encompasses social support, warmth, and feeling valued in children and adolescents. Recommendations for replication and future research are provided.