Communication is a critical skill for students to possess in preparation for college and their future careers. One way for students to communicate their ideas in all content areas is through writing. The English language arts portion of the Common Core State Standards (CCSSI 2010a) specifically states that students need to understand perspectives other than their own and comprehend, critique, and share their thinking through writing. Similarly, the Common Core State Standards for Mathematics (CCSSM) (CCSSI 2010b) calls for students to convey their mathematical ideas and understandings of concepts to their peers and to their teachers. Using writing as a communication medium helps students develop not only their English language arts skills but also their mathematical competencies. When writing, students must articulate their thoughts and put them in print, a process that ultimately helps them evaluate themselves as learners. The process of writing emphasizes gathering, organizing, revising, and clarifying thoughts, all of which endeavor to fulfill the Common Core's Standards for Mathematical Practice (SMP), particularly the third one, which emphasizes fashioning valid arguments while considering and critiquing others' rationalizations (2010b). Writing also can serve as a platform for students to convey their reasoning in a clear, organized manner. CCSSM as well as accompanying assessments set forth such expectations for students. These related assessments require students to do more than simply select one response from multiple-choice questions. Rather, students are asked about their reasoning and are obligated to convey this in writing. In this article, the authors present the use of debate journals as an innovative way to encourage students to construct mathematical arguments as well as examine and critique others' mathematical thinking.