The use of writing to learn mathematics at the university-level is a pedagogical tool that has been gaining momentum. The setting of this study is a second-year differential equations class where written assignments have been incorporated into the course. By analyzing survey results and students' written work, we examine the extent to which students view writing as an effective learning strategy, as well as their beliefs about the relationship between mathematical writing and communication. We also discuss what students' narratives reveal about their past mathematical experiences.