Ensuring all students have opportunities to engage in scientific argumentation is a key goal for K-12 students. While research has shown that teachers' beliefs about argumentation can impact their classroom instruction and that students in low socioeconomic status (SES) schools are less likely to experience challenging science learning, there is little research focused on the relationship between teachers' argumentation beliefs and student SES. As such, in this study we explored the scientific argumentation beliefs of teachers in low, mid, and high SES schools. Participants were 34 teachers piloting a curriculum with a focus on scientific argumentation. Our data sources included a survey and interviews. While our analyses suggest that teachers in all types of schools believe argumentation is important, we observed some differences between the teachers of high, mid, and low SES students related to their beliefs about the goals of argumentation discourse and student capability to engage in argumentation. These findings suggest that accountability pressures may impact the beliefs of teachers of low SES students in ways not experienced by teachers of high SES students and offer implications for professional development for such teachers.