Discourse connectives signal discourse coherence by making discourse relations explicit and by playing a role in the organization and structure of information in discourse. Therefore, their use in L2 writing is an important field of study that is likely to have implications for discourse competence both at the sentence-level discourse and at the level of larger discourse structure. The aim of the present study is to account for the use of three contrastive discourse connectives, but, however and although at both the microstructural and the macrostructural levels of discourse in the argumentative essays written by Turkish learners of English and native speakers of American English. The patterns of use by L2 learners are compared with those of native speakers. The analysis is based on 120 essays from two corpora: Turkish subcorpus of the International Corpus of Learner English (TICLE) and American subcorpus of Louvain Corpus of Native English Essays (ALOCNESS). The study reveals that the argumentative essays of Turkish learners of English and American students do not differ significantly regarding the three connectives neither structurally nor semantically. However, at the macrostructural level of discourse, differences concerning the pattern of argumentation and the role that the connectives play in the claim-counterargument-refutation pattern of organization were observed. Further analysis on other lexical items used in argumentation shows that in ALOCNESS, there is more reliance on other means, such as the lexical items expressing modality and those signaling the argumentative nature of the text.