Is there a language-based social disadvantage in solving mathematical items?

In Germany, academic achievement at school depends primarily on students' socioeconomic status (SES). This contribution tries to find an explanation for this fact and adopts a sociolinguistic point of view: the language used at school contains specific speech variants that differ from the language experiences of low SES children. It is language skills – predominantly learned within families, their social strata and cultural rearing – that influence to some extent the chances of successful participation in school. By using differential-item functioning, this article focuses on German items within the domain of mathematics (TIMSS 2007) to analyze challenge-determining characteristics in those items that are more difficult to handle for low than for high SES students.