The present study aims to investigate the effectiveness of a training programme targeted at United Nations (UN) staff interpreters who go on field missions. The UN deploys staff interpreters to ensure effective multilingual communication in field missions. Whilst being professional interpreters, however, these interpreters do not have any formal training in interpreting in the field, where they sometimes face situations for which they may not be properly equipped. Against this background, a joint training programme was organised by the Faculty of Translation and Interpreting, University of Geneva, and the United Nations Office at Geneva (UNOG) in January 2019. After the course, a mixed-methods study was carried out to evaluate its effectiveness. In this paper, the following aspects will be discussed: the particularities of UN field missions; the functioning and the contents of the programme; and the results of the study. Our findings show that, at the end of the programme, the participants felt better equipped to face the challenges of interpreting in the field. We conclude that training programme design must take into account the specific needs of the participants and the contexts in which they work.