This paper reports on a study that takes a problem-drive approach to answer the question “What do Mexican Spanish university writers ‘do’ when they write in Spanish, their L1, and in English, their L2?” This ethnographic study examines learners’ writing practices in their educational environment. Data collection includes learner and participant observation accounts, classroom observations, and textbook analyses. In Part I, the sociocultural context of the Mexican university is described, followed by a functional discourse analysis of one representative example from a multilingual student’s essay. Part II discusses the educational setting, literacy training, and writing instruction from both teachers’ and learners’ perspectives.