P r e s e n t a t i o n   During the last two decades, historians of science and philosophy as well as philologists have pointed out the enormous wealth and variety of scientific and philosophical texts written in the European vernacular languages throughout the Low Middle Ages. Philosophy, the health sciences, astronomy/astrology, etc. were no longer an exclusive patrimony of the learned language which dominated the academic discussions at the Universities, i.e. Latin, but became subject to the creation of technical treatises in vulgar tongues embracing all fields of knowledge from rhetoric to music, from medicine to arithmetic. While many of these new texts in vernacular were translations –mostly, though not solely from Latin– this development also gave rise to a large number of compositions ex novo of texts in vulgar tongues. The transmission in vernacular of a knowledge which was traditionally entrusted to the Latin language of monastic and academic discourse had important consequences for the languages of everyday speech which, from this very moment on, became languages of communication and culture in their own right. In this context, the study of the particular case of Catalan is an excellent point of departure, which allows to deepen our understanding of the issue at stake, since it is well defined and mapped, and offers a huge amount of first-class authors, such as Arnau de Vilanova, Ramon Llull and Francesc Eiximenis, who produced an outstanding corpus of vernacular texts. In addition, the situation of the Crown of Aragon as a territory of frontier and transition between the Islamic and Jewish Peninsular world and the Mediterranean and Northern regions of Christian Europe makes the case of Catalan vernacular most relevant: for being at the very crossroads of different linguistic and cultural traditions, it is this melting pot that brought out a significant part of the intellectual wealth of Europe, as we consider it today. The contributions to this ICREA Conference on Science and Society in the Crown of Aragon focus on central aspects of the phenomenon of vernacularisation, situating the case of Catalan vernacular in the context of parallel movements across Europe, and comparing it to the Latin-Hebrew translations which constitute a contemporary example of diffusion of knowledge in non-Christian communities of learning. For this purpose, the most renowned experts –national and international– covering all areas of knowledge and disciplines involved in the study of the process of vernacularisation have been invited to Barcelona.