This article describes findings from three successive empirical studies that examine the determinants of participation in transnational organizations by Latin immigrants in the United States, the character of the membership and activities of these organizations, and their bearing on the political incorporation of their respective communities. Results from these studies reveal that older, better-educated, and higher-status migrants are most likely to participate in transnational organizations linking them to their home countries. So are those with longer periods of US residence. Since migrants with these characteristics are precisely those with greater chances for US citizenship acquisition and participation in American politics, findings suggest that transnational activism and immigrant political integration are not at odds. Quantitative analyses of the determinants of political contact and political activism of immigrant organizations in the US indicate, unsurprisingly, that wealthier groups and those with a membership formed by better-educated and longer residents are most likely to be politically active. The societies left behind make a difference in the propensity toward political activism by different nationalities. Despite such differences, the overall trend is for immigrant transnational activism, individual and collective, not to retard political incorporation in the United States. Both processes occur simultaneously and appear, under certain circumstances, to reinforce each other. This conclusion contradicts both conventional assimilation theory and nativistic rhetoric. Contrary to assimilation expectations, older and better-educated immigrants rather than recent arrivals are those most likely to initiate and maintain ties with their home countries. Contrary to nativistic rhetoric, there is no zero-sum relationship between such activities and successful political incorporation to the United States.