The role of writing in the mathematics classroom is considered. Writing as a cognitive process and its relationship to problem solving is first examined. Then several long- and short-term techniques for promoting cognitive learning using writing in the mathematics classroom are considered. The Writing Across the Curriculum (WAC) program is discussed; some of its techniques can be adapted to encourage problem solving and cognitive learning. Suggested for the long term are: (1) a list of writing projects requiring several days or weeks to complete; and (2) a review method involving whole-class, individual, and group work. Short-term techniques usually require only a few minutes each day, but may take a whole class period. Discussed are explaining how, comparing two concepts, explaining why, doing word problems, outlining the chapter, developing test questions, doing proofs with prose, and keeping a notebook. Finally, how to get started is discussed, with note of the need for persistence. (MNS)