The ability to generate and assess formal arguments is essential if one is to participate effectively in civic and professional life. Developing students' argumentation skills is an important component of developing their capacity for higher-order thinking and their ability to use that skill to understand social issues. Too often, however, social studies teachers do not have the practical tools to help students develop argumentation skills. In this article, the author describes the development and assessment of an instructional tool to assist elementary school students in forming written arguments. (Contains 1 figure.)