Different kinds of arguments typically include claims, warrants, and evidence. However, the very nature of claims, warrants, and evidence are discipline specific. A student's essay, for example, may exhibit features of argumentation while revealing fundamental flaws in historical thinking. Stronger historical arguments exhibit historical thinking in their construction of claims and in their selection, integration, and explanation of evidence. Historical arguments begin with questions and sources and require an understanding of the original meanings of those sources, rather than using sources to support a predetermined point. I share data from different research projects with adolescents and historians to illustrate key aspects of historical argumentation such as noting author credibility or situating evidence in its historical context. Then, I show how teachers have supported students' growth in making historical arguments and why such efforts matter.