Students classified as English language learners (ELLs), many of whom are also Hispanic/Latiné/x, are at times excluded from opportunities to engage in engineering design experiences due to the emphasis on learning English. In dual language bilingual education, however, language policies that allow for the use and development of more than one language afford opportunities for ELLs that are not available in monolingual environments. We draw on a multilingual learning ecology theoretical framework to analyze data gathered from a two-year ethnographic study. During approximately 200 hours of field work, we gathered multiple forms of data through ethnographic methods, to include field notes from participant observation, interviews, photographs, and audio and video recordings. We show that participants enacted a multilingual learning ecology in which there was a space for both English and Spanish, but also hybrid language practices. Translanguaging, by either groups or individuals, mediated engineering design activities. The multilingual learning ecology also allowed students, many of whom were classified as ELLs, to agentively stretch their repertoire to engage in engineering biliteracy practices. These included identifying problems, proposing engineering solutions, building and testing a model, and communicating their findings.