ABSTRACT: The purpose of this Master’s degree project was to describe a professional translation internship at the Agency for the Prohibition of Nuclear Weapons in Latin America and the Caribbean (OPANAL). The first section includes a theoretical framework about the current literature on the topics of translation in a professional context and translation in international organizations. The second section describes the methodology used during the project. The third section presents a description of the internship itself. Lastly, there is a discussion and some conclusions resulting from the internship and its contrast with the different theoretical elements consulted. This project was carried out during the second half of 2019, as part of the second cohort of the Master’s in Translation program of the University of Antioquia. The internship on which it is based took place from 2 September to 29 November 2019 in Mexico City. Six fortnightly reports were generated and later analyzed in order to describe the main findings and contrast them with theoretical insights.