AbstractThe geographic expansion of Tiwanaku people and culture (cal A.D. 500–1150) in the south-central Andes can be viewed as a two-staged diaspora. This article defines and categorizes diasporas, suggests archaeological correlates and theoretical implications, and reconstructs the Tiwanaku diaspora. The first stage was a colonizing diaspora in the context of the functioning Tiwanaku state, limited to a few mid-elevation places such as the middle Osmore drainage near Moquegua and probably Cochabamba. The second stage was a much more extensive victim/refugee diaspora driven by the violent disintegration of the colonies around A.D. 1000, in conjunction with either the collapse of Tiwanaku or its radical reorientation by a militaristic elite. Second-stage diaspora populations that settled in sparsely populated areas such as the upper Osmore drainage or the Carumas–Calacoa region established dispersed, small, defensible villages. Those that settled among a larger or more established host population such as the Chiribaya in the coastal Osmore Valley integrated as a marked, lower-status minority. This explosive collapse suggests that Tiwanaku was composed of multiple groups whose differing interests could not be contained. Supporting evidence is drawn primarily from the Osmore drainage, especially the coastal segment.