This article presents and discusses a study that aims at establishing how self-mentions are used by pre-service teachers of English as a Foreign Language (EFL) in their argumentative essay writing. The study examined a corpus of argumentative essays written on a range of topics in EFL didactics by a group of pre-service EFL teachers (hereafter – participants). The corpus involved two rounds of argumentative essays written by the participants and their respective controls (nonteacher EFL students). The frequency of self-mentions in the corpus was analysed using the Statistical Package for Social Sciences (IBM 2011) in terms of raw values, and the computer program WordSmith (Scott 2008) as normalised data per 1000 words. The results of the quantitative analysis revealed that the frequency of the self-mention we decreased, whereas the frequency of the self-mention I increased in the second round of essays. These findings and their linguo-didactic implications are further discussed in the article.