This book is a cultural history of borders, hygiene and race. It is about foreign bodies: from Victorian vaccines to the pathologised interwar immigrant; from smallpox quarantine to the leper colony; from sexual hygiene to national hygiene to imperial hygiene. Taking British colonialism and White Australia as case-studies, the book examines the enclosures, boundaries and borders which were the objects and means of public health, as well as of colonial, national and racial administration between 1850 and 1950. If public health was in part about segregation (of the diseased from the clean, the fit from the unfit, the immune from the vulnerable), so was race a segregative practice in the modern period. Colonial management of race dovetailed with public health into new boundaries of rule, into racialised cordons sanitaires.