Prior research describes the positive benefits of dual language education as increasing students academic performance in addition to promoting bilingual development. However, these studies have not adequately addressed the tensions that exist in developing Latina/o communities bilingualism. This paper addresses the issue of bilingual development in the one-way and two-way classrooms where language separation is part of the program design. This is a qualitative and multi-site case study of two teachers from the U.S.-Mexico border. We draw on borderland theory to examine the ways the teachers supported their students bilingualism. Findings suggest that both teachers taught within the linguistic borderlands in their classrooms; each allowed students to go about languaging, or using language in interaction (Mignolo, 2000).