The 21st century has involved several changes at the social, economic, educational, health, etc. levels, brought about by events of different types, such as, for example, the constant conflicts in different parts of the world (including the Afghan conflict or the war in Ukraine), natural disasters caused by climate change, or health crises such as COVID-19 (Valero-Garcés and Alcalde Peñalver, 2024). These situations have often resulted in humanitarian crises that have involved large-scale population movements (Valero-Garcés and Alcalde Peñalver, 2024). This increase in population movements has been a challenge in itself as it has led to the configuration of new multicultural societies across the globe (Valero-Garcés and Lázaro Gutiérrez, 2016). This new reality implies not only coexistence but also access to basic public rights and services for the host population who does not speak the main language as well as the fulfilment of human rights (Vitalaru, forthcoming); in these different contexts, communication is essential. The very characteristics of PSIT, with its variety of contexts and situations, imply a series of challenges for different groups (users, service providers, and translators and interpreters) related to the provision and availability of services; provision and availability depend on the field in question, the availability of professionals for all the language combinations involved, the existence of training programmes, the quality of the training available, access to such training, etc. These challenges have been identified through the practice of the profession as well as through more specific research and are all related in some way to professionalisation. This article gathers some of the needs and challenges raised in different studies focused on Spain, as well as a summary of the topics covered in the articles included in this thematic issue of the journal. The contributions in this issue attempt to offer, from different perspectives (professional practice, training, and research), results, reflections, and actions considering the variety of PSIT situations and tasks. As this is a special thematic issue, the issue includes only articles and interviews.