In this systematic literature review, we synthesize and critically analyze information from publications between 2010 and 2020 that answer the following overarching research question: "What does being (or not being) advocates for English learner (EL) students look like for EL teachers?" Findings indicate that EL teachers' backgrounds and characteristics, such as gender, race, intercultural experience, and experience teaching, affect their propensity to advocate and the types of advocacy in which they engage. Additionally, we examine ways teachers advocate for their students inside and outside the classroom/school, such as changing how they instruct their EL students, and speaking up for them at district or states' departments of education meetings. We also explore and describe conditions that support (supportive administration, prioritizing ELs in the master school calendar, collaboration with general education teachers, for example) and hinder (unsupportive administration, marginalization of ELs and EL teachers, lack of collaboration with general education teachers, for instance) advocacy for ELs by EL teachers. Recommendations for pre- and in-service teacher education programs are offered, and potential areas for future research are also discussed.