The twenty-first century has seen an increased call to train students to craft mathematical arguments. The third of the Common Core's (CCSS) Standards for Mathematical Practice (SMP 3) (CCSSI 2010) calls for all mathematically proficient students to "construct viable arguments" to support the truth of their ideas and to "critique the reasoning" of others. The Common Core State Standards for Mathematics (CCSSM) recognize that students in the elementary school grades "can construct arguments using concrete referents such as objects, drawings, diagrams, and actions" (CCSSI 2010, p. 6). In particular, elementary school students often use examples when they make an argument. In this article, the authors offer a framework for helping teachers determine when such an example-based argument should be considered "viable" or not. They illustrate this framework with arguments they collected from a fifth-grade classroom and conclude by offering ideas that may help teachers support their students in making viable, example-based arguments.