Socioeconomic and language minority classroom composition and individual reading achievement: The mediating role of instructional quality

•SES classroom composition has an effect on reading achievement.•Proportion of minority students has no additional effect on reading achievement.•Teachers' focus on language may partially mediate the SES composition effect.•Student-oriented climate and classroom management do not play a mediating role.

In this study, we investigated effects of socioeconomic and language minority classroom composition on students' reading achievement and explored the mediating role of central features of instructional quality, namely focus on language, student-oriented climate, and structured classroom management. Analyses were based on data collected from 352 German ninth-grade classrooms across two measurement points (t1, t2) in a multilevel framework. We found socioeconomic composition to be related to individual reading achievement at t2 after accounting for the corresponding baseline assessment at t1. However, the proportion of German language learners had no additional effect on reading achievement. Our results also suggest that the effect of the socioeconomic composition on achievement may be mediated partially by the teacher's focus on language during instruction. We conclude that more attention has to be paid to providing equal opportunities to all students in language classes.