Nurses are regularly required to make clear and coherent written arguments. Formulating arguments is an important element of academic coursework for nursing students, while nurses are required to demonstrate evidence of their learning, reflection and continuing professional development as part of their revalidation. Improving their practice knowledge and skills also requires nurses to reason and express themselves in writing. This article explains how context contributes to the formulation of arguments and how to differentiate between argument and opinion. It details how premises and supporting information are used to underpin an argument. The article uses a case study to demonstrate how a coherent written argument can contribute to practice improvement.