Delft University of Technology (DUT) screened her (non-native English) scientific staff on their level of English proficiency in the academic year of 2006/2007. In this paper this large scale operation, involving planning, policy decisions, assessment means, advice and training are discussed. Since 2005 all the master programmes at DUT have been taught in English and since 3 years ago DUT has been an officially bilingual university with around 5,500 master students and 1,100 international students in the year 2008. Therefore, results are framed against the background of becoming an international university

Delft University of Technology (DUT) screened her (non-native English) scientific staff on their level of language proficiency over the year academic 2006/2007. In this paper the large scale operation, involving planning, policy decisions, assessment means, advise and training are discussed. Results are framed against the background of becoming an International University.