As firms have come under increasing competitive pressure to acquire and make effective use of knowledge that has been generated beyond their own boundaries, they are making increasing use of external recruitment of experienced scientists and engineers (SEs) who bring with them skills and knowledge gained in the process of working for other firms. This paper explores the impact of these developments on the returns to inter-firm mobility for individual SEs in the UK and France and finds that average returns to prior experience now match the returns to tenure over a large portion of scientists' and engineers' careers in both countries. The paper discusses some possible reasons for the similarity of labour market outcomes in the two countries, which is rather surprising given the much greater mobility of SEs in the UK compared with France