This study draws from sociocultural theory to examine how biographical factors interplay with contextual factors to shape the professional identity of a Spanish language teacher candidate. Specifically, it explores the student teaching experience of Marcos, a 30-year-old language teacher candidate from South America. Analysis of the data reveals that in forging his professional identity, the participant appropriates discourses that place high value on native speakerness and male authority. While this allows him to claim legitimacy as a Spanish language teacher, it also leads him to assume a taken-for-granted view of both subject matter knowledge and classroom management skills, precluding his development as a teacher. Implications derived from this study call for a critical language teacher education that provides tools for examining unquestioned assumptions about language and gender ideologies, expanding identity options, and fostering professional agency. (Contains 2 notes.)