This paper summarises the findings of a questionnaire study investigating the language pro-files and practices of cross-border workers in Luxembourg. The study was undertaken in 2009 and includes 128 cross-border workers from 35 workplaces from different sectors, including the health sector, higher education and research, the manufacturing industry and the service sector. The study suggests that all the participants have a multilingual profile and have learnt at least one language in addition to their first one in the course of their life. A second result is that French is used in all the workplaces under investigation. But, at the same time, the major-ity of the cross-border worker participants have a multilingual professional life, most of them using more than one language at work on an everyday basis. This multilingualism comes in the form of a wide range of multilingual practices, including language accommodation, use of a lingua franca, code-switching and receptive multilingualism. Furthermore, two thirds of the participants report having learnt Luxembourgish either formally or informally, and half of those who have not learnt it, would like to do so in the future.