The OSG De Ring van Putten is a public secondary school located in Spijkenisse, the Netherlands. We offer various types of education, among which the bilingual stream in pre-university education. In this department pupils attend classes that are offered in both Dutch and English. Internationalisation plays a significant role in our bilingual department. A good command of the English language is not a goal as such but serves more as a means to, among other things, communicate (e.g. during pupil exchange programs). It also provides our students with the opportunity to learn how to be an adequate part of an international society. A skill that is not only of great value now but will very much continue to be so in their future careers. The main objective of this application is to expand the knowledge base and further improve the language skills of seven of our employees who are currently teaching our bilingual classes. Improvement of their language skills is not the sole focus, it is also about extending their knowledge of the CLIL methodology that is inextricably linked to bilingual education. All seven teachers are in possession of a Cambridge Advanced or Cambridge Proficiency Diploma. We opt for professionalization in the United Kingdom because it allows us to work on improving and extending our English language skills and CLIL methodology in a relatively short period. Considering the international setting of the courses it will also provide us with the opportunity to make contact with colleagues from abroad. The professionalization meets both the short term and long term goals in making international contacts.