The aims of this investigation are to create an overview of how Norwegian upper secondary school students use modality markers in formal argumentative essays; if – and if so, which –modality markers the students use; and to what extent writer visibility is present in these student texts. Two study programs are compared in order to find any differences. These are the International Baccalaureate Diploma Programme (IB) and Studieforberedende utdanningsprogram (SF), where two classes represent each program. Argumentative essays from each of these classes were collected and analyzed through the use of the corpus freeware AntConc and calculating relative frequencies. The findings indicate that SF students use downgraders and upgraders more often than their fellow IB students. They also demonstrate more frequent use of downgraders than upgraders in all four schools and a general adherence towards using the downtoner, agent avoider and intensifier in particular. Differences between the two study programs involve for instance the SF students using the lexical teddy bears I think and just to a greater extent than do the IB students. The results also show a stronger indication of writer stance in the text (for example, through a more frequent use of first-person singular pronouns) whereas IB students use such modality markers to a lesser extent. These findings may be impacted by, for instance, time restrictions given for writing the essays (test situations vs. homework), essay topics, register awareness and a stronger reliance on genre conventions pertaining to Norwegian-speaker or English-speaker language norms. Greater awareness of students’ use of modality markers according to register may contribute to aid teachers in the teaching of appropriate register with respect to the genre norms set for the students to learn according to their syllabus and/or curriculum. Furthermore, it may also contribute to a greater understanding of differences in genre norms in various speech communities and thus allow for the students to adapt their language according to the expectations of this community if necessary.