This article examines a collaborative study group's discussions about "revoicing," an idea from linguistics that has been identified as an important discourse strategy in the teaching of mathematics as well as other content areas. This group, made up of eight middle grades (grades 6-10) mathematics teacher-researchers (TRs), one university professor, and two graduate students in the United States, is involved in a longitudinal study with the purpose of better understanding how doing action research on their own classroom discourse impacts mathematics TRs' beliefs and classroom practices. Using qualitative research methods, we examined transcripts from 18 project meetings to understand how the teachers talked about revoicing as well as how their understandings of this idea changed across time. We contend that collaborations with teachers can provide rich developmental views of how teachers come to understand aspects of their classroom discourse. (Contains 2 tables.)