The right to birth registration is a fundamental human right consecrated in Article 7 of the United Nations Convention on the Rights of the Child. Despite the fact that Mexico's Senate ratified the Convention in 1990, the statistics regarding the under-registration of births in the world and in Mexico are alarming. The most recent estimations of the national index of opportune birth registration in Mexico report average to high numbers, but these national statistics hide enormous variations amongst Mexican states. It is no coincidence that this problem disproportionately affects the states with large populations of indigenous peoples, such as Chiapas, Guerrero, and Oaxaca, since these are the groups already living on the margins of society. If living without birth certificates implies that Mexican children do not exist or are invisible, then migrating to the United States without a birth certificate multiplies their problems, as they are then "doubly undocumented" and deprived of many basic rights, resources, and opportunities. These migrants' situation of double vulnerability has converted them into victims of statelessness and of the indifference of the Mexican government by way of their consular offices in the United States. On the forefront of a campaign to get all Mexicans registered domestically and abroad is the non-governmental organization (NGO) Be Foundation: Derecho a la Identidad. This NGO was a driving force behind the Reform Initiative of Article 4 of the Mexican Constitution, which officially passed the Senate on March 13, 2014. The reformed Article guarantees the right of all Mexicans to a free and opportune birth registration and seeks to facilitate the process by requiring certain formatting standards for all birth certificates. Despite becoming an important negotiating force and advocacy network within Mexico, questions arise about Be Foundation?s ability to bridge this national legislation with local capacities, especially with unregistered migrants living in the United States. This thesis examines the binational issue of under-registration and the "double invisibility" of Oaxacan migrants in California, by comparing the advocacy efforts of Be Foundation with that of the Indigenous Front of Binational Organizations (FIOB), in order to understand the ways in which different social actors deal with the issue of birth registration on both sides of the border. The thesis poses the following research questions: What are the advocacy roles of these organizations in regards to the issue of doubly undocumented Migrants living in the United States? How did such a small organization manage to pull off a national constitutional reform? Has Be Foundation aligned itself with migrant organizations such as FIOB in order to create a transnational advocacy network committed to their cause, or is their network primarily national? Considering the strong transnational network that already exists within the Oaxacan migrant community, how important is the advocacy role of Be Foundation to migrant organizations that operate primarily in California, such as FIOB?