Debating is an important activity offered to all students. Apart from aiding skills in research, logic and clear thinking, debating develops self-confidence, fluency and team work. Marcellin promotes teams at all year levels and organises inter-school debates as time allows.

Marcellin has teams competing in the School Competition of the Debating Association of Victoria, a Catholic Schools Competition, as well as entering students as individuals for students and all students are warmly invited to participate.