This paper deals with some aspects of English for professional purposes. After a short historical overview of theories related to LSP (language for special purposes), we focus on some of the linguistic peculiarities of English for Specific Purposes. Our aim is to make a synthesis of the main theories and debates upon the issue of specialized languages, as the number of articles and writings on the topic is tremendous. We also wish to make a brief presentation of the most important contributions (still, we have to admit that the list of authors and articles is much longer, we had to make a selection, due to the editorial limitations of this article). We have gathered and synthesized what authors like Cabré, Celce-Murcia, Crystal, Croitoru, Motos, Strevens and others have said and we have also tried to make a comprehensive list of the names given to