Advocacy for English learners (ELs) is a clear expectation of English to speakers of other languages (ESOL) teachers, yet we do not fully understand what ESOL teachers do as advocates or the factors that play a role in determining if and how they advocate. This article reports the results of a quantitative study that explored the “what” and “why” of advocacy actions of in‐service ESOL teachers. Survey data (n = 511) reveals two types of advocacy actions, instructional and political, with ESOL teachers more likely to carry out instructional advocacy. Knowledge of the TESOL teacher preparation standards, being in an advocacy‐supportive school environment, and having advocacy self‐efficacy predicted greater instructional and political advocacy actions. More years teaching, teaching in a middle or high school rather than an elementary school, and being racially diverse also predicted more political advocacy actions. Implications for TESOL teacher education programs include ensuring all teacher candidates understand the inclusion of advocacy in the TESOL teacher preparation standards, explicitly teaching advocacy skills, and highlighting the importance of collaboration to build relationships and supportive school climates. More research is needed to better understand the connections between social justice and advocacy dispositions.