While medical quarantining has (again) received widespread attention during the COVID-19 pandemic, comparatively little consideration has been given to how medical quarantining is entangled with socio-political life. Further, there are no known studies that consider how quarantine might also be employed as a socio-political practice. This article explores the concept of social quarantine by tracing the creation of white Australia via the social construction, excise and discipline of Indigenous peoples as a potentially contagious Other. It shows how social quarantine integrates largely disparate sociological concepts/literatures (e.g. bordering, (im)mobility, confinement, enclave society, discipline, eugenics, assimilation), demonstrating how they unite under settler colonialism as a powerful assemblage of disciplinary technologies. Social quarantine also makes visible how the threat of contamination has been central to constructing and protecting Australia’s (white) imagined nationhood from the perceived disease of Otherness.