This article describes bilingual teacher preparation at a public university on the U.S.-Mexico border. I examine colonizing language ideologies that are reproduced in the local schools and teacher preparation programs, and show how preservice teachers engaged in Participatory Action Research to counter negative ideologies about bilingualism and bilingual children (Flores 2013). Through the use of decolonizing pedagogies (Tejeda, Espinoza & Gutierrez, 2003) aimed at disrupting a cycle of linguistic and cultural reproduction, participants learned to question and challenge deficit views toward Mexican-origin and bilingual learners. Alternative pedagogies included language and literacy autobiographies, case studies of emergent bilingualism, and analysis of the local linguistic landscape. I show that decolonizing pedagogical tools are necessary for transforming persistent negative ideologies about Spanish and Tex-Mex that continue to silence many children and teachers in the region.