In this chapter, three cases are treated collectively and systematically in order to emphasize similarities and contrasts among them. The most obvious similarity is the minuscule size of the indigenous population, which in each country lies somewhere between 1 and 3 percent of the total. These indigenous populations are internally heterogeneous and widely dispersed. Most Indians live in mono-ethnic indigenous communities located far from the capital city and many are pressed to the frontiers of national boundaries. Indigenous social movement organizations independent of state tutelage formed in all three countries in the early 1970s and linked themselves to the transnational indigenous rights network that emerged at the end of that decade. The political contexts also share similarities, most importantly a tendency toward decentralization in the 1990s. All three societies are primarily urban and industrialized, but are encircled by a more traditional, conservative landowning class. It is the key contrasts between Colombia and Venezuela, on the one hand, and Argentina, on the other, that explain the variation in the propensity of successful ethnic parties to form in each country. In Colombia and Venezuela indigenous movements were relatively united and institutionalized prior to the opportunity for major constitutional reform. In both cases, indigenous peoples' organizations participated directly and successfully in those reforms, producing two of the most progressive régimes of ethnic constitutional rights in the region. In both countries, these rights included reserved seats for indigenous candidates. [ABSTRACT FROM AUTHOR]