Research on teachers' beliefs has demonstrated that beliefs have an important impact on teachers' practice. In teacher feedback research, however, not much is known about teachers' beliefs and the extent to which they influence practice. This article reports on the findings from a study that investigated teachers' beliefs and practice in written feedback from two sources: (1) feedback analysis based on 174 texts collected from 26 teachers and follow-up interviews with seven of them; (2) a survey comprising a questionnaire administered to 206 secondary teachers and follow-up interviews with 19 of them. While the first data source investigated teachers' actual written feedback, the second source focused on teachers' beliefs and reported practice, both followed up by interviews that probed teachers' beliefs and practice. The article presents the salient findings in terms of ten mismatches between teacher beliefs and practice in written feedback and concludes with implications arising from the study.