This paper focuses on educational inequalities in multi-ethnic Basque secondary education. More precisely, the study takes an ethnographic standpoint and aims to explore the academic performance disparities between autochthonous and immigrant students in Basque education in relation to teacher authority. Methods include participant observation and interviews conducted in a Basque school attended by a high proportion of immigrant students. The data indicates that teachers showed three kinds of authority styles, including authoritative and affectionate, which elicited different degrees of student autonomy. The authority style that did not elicit an effective student response involved the use of both authoritative and affectionate strategies; this inconsistent style was only observed when teachers interacted with immigrant students around Basque language learning. This paper argues that teachers' authority styles have implications for the academic inequalities present between autochthonous and immigrant students. [Paper presented at the Oxford Ethnography and Education Conference, 2018.]