Background Aims of the current study were to investigate social connectedness as an identity component of belongingness that is distinct from social support and of potential interest in health research. Methods Social connectedness identity (SCI) and health factors were measured in a sample of college students (Study 1, n = 486) and a sample of individuals with ongoing symptoms of chronic illness (Study 2, n = 225). The third study added loneliness and stress measures to explore SCI as a potential antecedent in a serial mediation model (Study 3, n = 280). Results SCI emerged as a significant and independent predictor of physical symptomatology, physical functioning, and general health. In Study 3, serial mediation findings showed that the stress of loneliness explained the connection between SCI and health. Conclusions Results from the three reported studies identify SCI as a belongingness identity concept that warrants further study in reference to health and loneliness.