This case study investigated a modern language teacher candidate’s developing translanguaging stance in a Masters-level TESOL course as she made sense of emerging tensions while drawing on her personal and teaching experiences. Data included the participant’s oral contributions to the course, the course syllabus, and student-produced artifacts. We used thematic analysis focusing on the participant’s perceptions of translanguaging as both theory and practice to analyze the data. A semi-structured interview was carried out five years later to review the impact of translanguaging on the participant’s teaching and ideology as a Spanish teacher in a dual language program. Findings uncovered five primary themes all related to the participant’s biographically related development of translanguaging stance: traditional second language acquisition theories as a concern, updating the notion of social justice, the ability to support positive identity development, contemplating translanguaging as a pedagogy, and the longevity of the biographical approach to lifelong learning. The findings highlight the importance of biographical approaches to lifelong learning in language education and suggest that teachers can foster bilingual development, establish inclusive teaching strategies, and create equitable language learning spaces by recognizing the potential of translanguaging, which may be made possible by fostering similar contexts in teacher education courses.