This article contributes to a growing conversation of teachers' advocacy for marginalized students. We follow a cohort of teachers' advocacy from their English as a second language certification courses into their work in one linguistically diverse school district. Dialogic discourse analyses of 3 years of discussions show the types of advocacy in which the teachers engaged, and identify five foundational discourse moves teachers employed to develop ideas and manage the relational complexity of advocacy. Findings provide evidence of the important role of intertextuality: voices across time and texts facilitated the teachers' advocacy efforts. We offer a revised definition of language teacher advocacy to emphasize its discursive nature, arguing that an examination of the dialogic processes of advocacy work can help better delineate how it develops iteratively, contextually, and not always successfully. We implicate teacher education as an important catalyst for the preparation of teachers' advocacy for under-served and historically marginalized English-learning students.