This study investigated 309 secondary mathematics teachers', from 50 school districts, perceptions of Writing to Learn Mathematics (WTLM) strategies. A modified version of a previously validated instrument was used for an online survey (Silver, 1999). Only 45% of teachers who participated in the survey were familiar with WTLM. The majority of these teachers reported significant or some effect on student achievement in mathematics when using WTLM; however, half of these same teachers reported that WTLM required too much class time. The majority of teachers also reported at least some positive effect on student attitude in mathematics when using WTLM. Chi-squared results suggest that teachers' use of WTLM varied by teaching level. Also, teachers with higher use of WTLM had higher perceptions of effectiveness and more positive attitudes. Results indicated that the time teachers have with students and the many job requirements became obstacles for implementing WTLM.