This study deals with the computer-aided analysis of interlanguage errors made by the participants in intercultural telematic simulations involving university students and professionals from five European countries. The simulation involves the participants in producing a large amount of written discourse, all in English, which is composed and sent via computers as either synchronous or asynchronous communication. Using the Error Tagging Method and Error Editor developed by the Centre for English Corpus Linguistics at the Université Catholique de Louvain in Belgium, the interlanguage errors, as regards the morphological and lexical aspects, were identified, classified and tagged, while the corrected versions of the deviant forms were added. The following research questions were formulated: 1. Are there more errors in the synchronous or asynchronous mode of communication? 2. Is there a difference in the type of error to be found in each mode of communication 3. Do the different groups have more errors of some types than others? 4. Do the different groups make errors that can be associated with their particular first language (L1), in other words, does the L1 influence the type of error predominant in any one group? 5. Looking in greater detail at the Spanish participants output we enquired which errors were salient in these subjects? 6. Can we identify the causes of these salient errors in the Spanish L1 group? In the section referring to the theoretical background to our research work, we begin by making reference to the interrelationship of the different functions of language depending on the contextual situation of the communicative event, in our case, as observed in the telematic simulations. We then focus on the notions of communicative competence, and error, from both a historical perspective and with regard to their significance in English as a Foreign Language teaching. The role of Information and Communication Technology in language teaching pedagogy finalises the first section of the thesis. The corpus comprised 42,059 words in the synchronous mode, and 42,625 words in the asynchronous mode. A Correspondence Analysis was carried out with the aim of verifying the relative incidence of error types according to the L1 of the participants by investigating the different variables and their effect on the type and frequency of the errors, depending on the mode of communication. As regards the answers to the research questions formulated, there were indeed more errors in the synchronous mode of communication than the asynchronous, as we hypothesised, although when examining the exact types of errors, some categories were more frequent in the synchronous mode (the formal and grammatical errors, among others), while in the asynchronous, errors of style and lexis were higher. A further analysis of the data revealed that the frequency of error types varied with each different L1 group participating in the simulation, and when the Correspondence Analysis was carried out, this showed that highly relevant associations could be established as regards the relation between participants L1 and specific error types. After examining the results, we concluded that the L1 of the learners does in fact influence the type of error made. Following this comparative analysis of interlanguage output, we focused on the errors in the corpus made by the Spanish L1 group, classifying them, and commenting on their nature and frequency. The results obtained revealed that mother tongue interference appears to be the cause of a significant number of errors in the formal and lexical categories. __________________________________________________________________________________________________ RESUMEN La investigación que se llevó a cabo en la elaboración de esta tesis presenta el objetivo fundamental de abordar un análisis exhaustivo de los errores interlingua acaecidos en un tipo de comunicación intercultural donde el discurso es de tipo síncrono en tiempo real y, asíncrono en tiempo diferido. El corpus analizado procede de la comunicación escrita entre grupos multidisciplinares que participan en una simulación telemática a distancia a nivel internacional. Los sujetos participantes proceden de cinco universidades europeas localizadas en Noruega, Latvia, Alemania, Francia y España. El estudio demuestra que existen ciertos tipos de errores que se repiten con mayor frecuencia, dependiendo del modo de comunicación. De igual modo, indica que hay categorias de errores que se dan con mayor frecuencia dependiendo de la lengua materna de los sujetos participantes en la simulación. Por último, se llevó a cabo un sub-análisis de los sujetos españoles, cuyo resultado demuestra que la interferencia de la lengua materna es una de las causas principales de los errores formales y léxicos de este grupo de participantes