Teachers and students agree that despite the time-consuming nature of providing written commentary and revising using this commentary, teacher feedback is both desirable and helpful. Nonetheless, teachers express concerns about how to provide commentary in ways that their students can effectively use to revise their texts and to learn for future texts. This paper addresses these concerns by helping teachers identify the issues to which they need to attend and by sharing effective practices they can use in providing written commentary to rhetorical and content issues in their students' writing. The paper first addresses the role of the context within which commentary and revision take place, delineating the issues that teachers need to be aware of and the questions they can ask about context to help guide decisions about commentary. The paper next addresses the process of communication between teachers and students, describing ways of providing such communication that will enhance the effectiveness of the teacher's commentary and the students' revisions. The final sections discuss the shape of teacher commentary, with recommendations for what factors teachers can consider in deciding what to comment on as well as recommendations for the forms that effective commentary take.