This paper reports on empirical research, the purpose of which is fourfold. Firstly, we provide data regarding the realization patterns of requests made by Canarian Spanish students, both orally and in writing, in their mother tongue, a variety of Spanish. Secondly, since these undergraduates study English as a Foreign Language, we also examine the requests they make as non-native speakers of English. Two different methods were adopted for data elicitation, namely, open tape-recorded role-plays and Discourse Completion Tests (DCTs). Thirdly, we obtained a corpus of natural data through field notes taken from an array of real interactional situations in which different people spontaneously formulated requests. Finally, we try to determine to what extent the results in each phase differ depending on the method and the language used, thus contributing to the debate on the validity of research methods