The main objective of this study is to establish that explicit teaching of argumentative writing in secondary schools can not only give students access to a vital genre of power in our society but also develop their thinking skills. Here, the term 'explicit' teaching refers to the genre-based approach to teaching writing which advocates the teaching of text purposes and structures explicitly. More specifically, the teaching model which is adopted is the curriculum cycle introduced by Martin and Rothery (1986). Because of the constraints of this study as well as the needs of the students, this curriculum cycle is adapted and implemented with a small group of secondary three students. After conducting a total of ten lessons, a comparative analysis of the beginning and final compositions that the participants did during the teaching cycle is carried out. The topic for these compositions is the same but the participants wrote their first attempt before implementation of the cycle and the second attempt at the end of the teaching cycle. The set of cognitive-cum-linguistic criteria designed for the comparison establishes that the genre-based approach to teaching argumentative writing has allowed for an increase in the complexity of the students' language use and thinking.