Transnational youth represent an increasing demographic in societies around the world. This circumstance has amplified the need to understand how youths' language and literacy repertoires are shaped by transnational life. In response, this article presents a case study of a Mexican adolescent girl who immigrated to the United States and continued to participate in life in Mexico. It examines shifts in her multiple language and literacy practices that she attributed to transnational life and the knowledge she acquired from transnational engagements with languages and literacies. Data include interviews of the young woman, observations of her in a variety of social contexts, and literacy artifacts that she produced. Research on transnational youths' language and literacy practices and theories of multiliteracies and border crossing facilitate analysis. Findings include that language and multiliteracy practices shift in interconnected ways in response to transnational life and engagements with multiple languages and literacies foster transnational understandings. Accordingly, attending to transnational youths' multilingual as well as multiliterate practices can deepen understandings of how people recruit multiple languages, literacies, and lifeworlds for meaning making. Implications of this work are offered concerning the features of a transnational curriculum that can both draw from and build up the language and literacy reservoirs of transnational youth. (Contains 2 figures and 1 note.)