This article reports on an analysis of academic essays written by two groups of second-year university students: one group with History as a major, and a mixed group. The analyses focused on key features representing each of the three main functions of language identified in Systemic Functional Linguistics. The ideational function is represented by logical relationships, the interpersonal function by appraisal, and the textual function by thematic development. The main finding was that students in the cross-disciplinary group acquired a more marked command of stance and engagement than the members of the subject-specific group. They also acquired a more varied repertoire of lexico-grammatical devices that facilitate cohesion and mark logical relationships. Students in the two intervention groups improved about equally in terms of their ability to develop an argument systematically. The results showed that a visible pedagogy and ample opportunity for practice are effective, irrespective of the scope of the intervention.