This study explores biliteracy as understood and practiced in school and community contexts in a particular region of the US-Mexico borderlands, the Rio Grande Valley of southeast Texas. Drawing on capital theory, we contrast the ambivalent perceptions of Spanish/English biliteracy held by local pre-service and in-service educators with biliterate practices that are highly visible in the border communities where they live and teach. One objective of the study is to describe the diglossic nature of bilingualism and biliteracy in the Valley as a context for learning and teaching. We highlight patterns of overlap and difference in the ways that biliteracy is positioned in and out of school in this remarkably bilingual region, and we apply theories of human capital to interpret these patterns. A second objective is to share pedagogies for repositioning biliteracy through teacher education and to suggest directions for further research. (Contains 6 figures.)