Of all the various infections that afflicted Aboriginal people in Australia during the years of first contact with Europeans, smallpox was the most disastrous. The physical and social impacts of the disease are well known. This article considers another effect of the contagion. It is argued that a nativist movement in the form of a waganna (dance ritual) associated with the Wiradjuri spirit Baiame and his adversary Tharrawiirgal was linked to the aftermath of the disease as it was experienced at the settlement site of the Wellington Valley of New South Wales (NSW). The discovery of this movement is of considerable significance for an understanding of Aboriginal responses to colonization in southeastern Australia. It is the earliest well-attested nativist movement in Australian ethnohistory.