<p>Educative science curricular materials can influence teachers’ pedagogical practices, curriculum modifications, and in-the-moment shifts to center emergent multilingual learners’ sensemaking. Linguistic and multimodal representations, such as gestures and diagrams, are intrinsically linked to sensemaking and communication in science classrooms aligned with&#xa0;reform-oriented science instruction <i>reform oriented science instruction</i>. However, it is unclear what and why teachers customize curriculum to support emergent multilingual learners’ use of linguistic and multimodal representations for scientific sensemaking. In this study, we investigated how teacher beliefs about language and their schools’ language policy contexts related to the types of customizations for emergent multilingual learners they reported making to open&#xa0;educational resource science curricular materials. We employed a cross-sectional survey design with follow-up interviews to gain a more nuanced perspective from a subset of teachers. Our analysis included both descriptive analyses of Likert-style teacher beliefs data and qualitative coding of teachers’ survey and interview data. Findings suggested that teachers who worked in schools with restrictive language policies did not tend to welcome emergent multilingual learners to use their home languages in science, while teachers who worked in schools with more expansive language policies tended to welcome students’ home languages for science learning. Additionally, teachers’ curricular customizations tended to align with their beliefs about language in science—whether customizing to welcome multimodal communication or customizing to focus on students’ acquisition of English. Importantly, this work highlights tensions between some teachers’ beliefs about language in science and school-based expectations about customizations for emergent multilingual learners.</p>