A deeper interpretation of world language (WL) teachers' ideologies toward language learning and students' languaging practices can provide us with a different lens through which to understand teachers' teaching practices in language classrooms. This study adopts the attitude system of systemic functional linguistics (e.g., Martin & White, 2005), specifically the features of affect, judgment, and appreciation, to explore one elementary Mandarin WL teacher's ideologies regarding language teaching and language use. The data were collected through semi-structured interviews with the teacher-participant from an ongoing ethnographic study. Findings indicate the Mandarin teacher's alignment with "the younger, the better" language acquisition stance and her multifaceted perspective on bilingualism. While she acknowledged the cultural capital of Chinese, she exhibited fluctuating views on students' home languages and home language use. Based on the findings, we suggest the need for future WL teacher training and professional development programs to guide teachers in identifying and reflecting upon their implicit ideologies about language teaching and learning, as well as students' linguistic resources.