The study of multilingualism has gained prominence due to increases in linguistically diverse student populations. This paper aims to contribute to research on multilingualism by addressing schoolteachers' beliefs and practices related to linguistic diversity. A unique sample of 606 teachers across ten minority-dominant schools from Southwest China participated in the survey study. The results show that schoolteachers hold both monolingual and multilingual beliefs. Teachers' beliefs are mainly positive about multilingual education, and they favor supporting multilingual teachers. However, students' home languages are viewed as the barrier to the school success. Furthermore, many teachers rarely implement linguistically responsive teaching practices. A moderate correlation was found between teachers' beliefs and linguistically responsive teaching practices. Additionally, regression analyses show that teachers' linguistically responsive teaching practices can be predicted by age, gender, language background, travel experience, international news exposure, and culturally relevant teacher training. These findings indicate an urgent need for teachers to participate in professional development to become better equipped to advocate for multilingualism and effectively address the realities of language minority students.