In this chapter we will use learner corpora to examine how learners of English qualify the claims they make in argumentative essay writing. In doing so, we will be working within the tradition of contrastive rhetoric, but using the corpus methodology. Learner corpora are collections of language data gathered from non-native speakers/w riters of English. T hough the precise origin of the idea for the construction of learner corpora remains contentious, it is uncontroversial to say that during the 1990s an increasing num ber of learner corpora have been collected, such as the ICLE,1 LLC2 and HKUST corpora.3