Abstract This article reports on the academic performance and experiences of non-native university students, specifically German students in a Dutch academic environment. These students have a substantial dropout rate. In an earlier study, we found correlations between results on language tests and study results. In this study, we used semi-structured interviews with student advisors, students and teachers to investigate in more detail the role of foreign language proficiency in academic success. We identified three major language-related issues: (1) listening and speaking in discussion groups, (2) writing in examinations and assignments, and (3) the negative impact of language proficiency on grades. The quality and readability of the written assignments was repeatedly highlighted as the core problem. Additionally, we investigated the influence of the use of English as an additional foreign language.