This book reports on a study that analyzes students' perceptions of the benefits and drawbacks of using writing as a teaching tool in mathematics. The types of writing students performed in mathematics classes are described, and students' preferences regarding these tasks are analyzed. Finally, a comparison is made between female and male students' responses in order to see whether gender played a significant role in shaping students' perceptions of writing as a tool for learning mathematics. Students' writing samples included show how the students were learning to use writing to explore alternative solutions to problems and also to check and reflect on their understanding of new mathematical concepts.