The study reported in this paper investigated the pragmatic aspects of task-performance in a series of argumentation tasks that 24 Hungarian learners of English performed over a period of two years. The aim of our research project was to determine how task-repetition, the long-term development of language skills, and a short-term focused intervention influenced various pragmatic measures of task-performance such as the pragmalinguistic markers of argumentation, the number of claims, counterclaims, supports and counter-supports. We also analysed how these variables differed when the participants performed the same type of task in their mother tongue. The results showed that in the repeated version of the task, familiarity with the task structure helped learners pay more attention to the informational content of their message, which was reflected in the higher number of supportive moves they produced. Participants were found to have better argumentation skills in their mother tongue and used a wider variety of pragmalinguistic markers than in L2. The language development assumed to have taken place during one year and the argumentation training, however, did not result in better pragmatic and pragmalinguistic performance.