Based on ethnographic research from 2002 to 2007, this paper examines the historical and social mechanisms behind the border-crossing activities of Fujianese undocumented immigrants migrating into Taiwan. The thesis of this paper is fourfold. First, these immigrants' social linkages cross the Taiwan Strait, based primarily on kinship networks, were first established during the Chinese Civil War (1945-1949). Second, from the late 1980s to the early 2000s, Fujianese immigrants made their illicit entry into Taiwan possible mainly by resorting to the social rules inherent in these kinship linkages. Third, as a result of the increasingly stringent border-control policy exercised across the Taiwan Strait over the past decade, fraud marriage has become a primary means of border-crossing, thus resulting in a completely new way of understanding and practicing immigrants' social relationships in Taiwan. Lastly, in an era of globalization, the sovereign power of the nation state, as embodied chiefly in the functioning of border control, is now the primary force regulating the lives of nation/race boundary-crossers.