This study investigates the impact of the presence of students identified as having special needs (SEN) on their classmates' achievements in reading comprehension. Multi-level regression modelling was conducted with the data of more than 75,000 fourth graders of 4,937 classes in Austria. Students' scores of reading comprehension were used as the dependent variable in the models. The number of students with SEN was used as the independent variable, besides other class-level predictors like the socio-economic status or the self-concept. To disentangle individual from classroom composition aspects, variables at the individual level were used as independent variables as well (gender, age, first language, number of books at home, socio-economic background, kindergarten attendance, and self-concept). Results show only a small relationship (Cohen's d = -0.16) between the presence of students with special needs on their classmates' national standard scores, in particular compared to other class-composition effects like socio-economic status or self-concept.