The Next Generation Science Standards (NGSS) call for students to exhibit an in-depth understanding of scientific inquiry practices, including direct observation, creative design thinking, and argumentation based on evidential learning. To support academic equity for multilingual learners, these new expectations require reconceptualization of science teacher education and classroom instruction, whereby emphasis is placed on incorporating the linguistic and cultural repertoires of learners through multimodal and open-ended learning activities. To support this shift in practices, this paper presents a culturally sustaining systemic functional linguistics (CS SFL) framework for science teachers and multilingual classrooms. CS SFL praxis emphasizes three intersecting areas: language development, knowledge development, and cultural sustenance.