Specifications in England and Wales frequently cite improvement in the quality of students’ arguments as a key objective of courses of study for public examinations. More generally, this objective might be seen as a central element in the process of citizenship education. However, there is evidence that progress in the quality of students’ arguments is disappointing relative to other dimensions of their achievement. Research evidence on the differences between informal and formal arguments provides a basis for identifying weaknesses in students’ arguments that might be addressed in teaching. This evidence also suggests ways in which these weaknesses might be addressed. However, this literature provides a generic account of the development of argument, rarely paying attention to differences between different subjects. Drawing on this literature this paper describes an approach to supporting the development of students’ arguments within two curriculum subject areas: geography and business studies. Similarities and differences between the subjects are identified and the way in which these characteristics of arguments have been used with students to develop their arguments is exemplified.