Under specific conditions, writing students effectively use teacher commentary when revising current essays and composing subsequent assignments. Writing instructors who are aware of these conditions can more efficiently help students improve their writing as well as minimize the time they spend evaluating student essays. The findings of this case study are based upon exploration of six first-year university writers' argument and rhetorical analysis papers. Future research might focus on other genres, contextual effects, and the revision decisions of composition students who speak English as a second language. Students appear to read and apply end comments that offer praise and feedback when such comments appear on an intermediate draft of a work in progress. Students rely on marginal comments, not terminal comments, to revise targeted expression problems.;Therefore, instructors might save time by withholding terminal comments on expression and providing detailed marginal comments on expression. Further, students effectively apply comments that target content when revision can be made without disturbing the existing text. Students appear to ignore comments that target content problems if implementing the suggestions therein requires extensive revision of a work in progress. Also, students are more inclined to ignore terminal comments on organization than they are to implement them as they revise works in progress. On the other hand, those comments, if written as terminal comments on final drafts and stated as goals for future writing projects, effect improvement in the students' subsequent essays within the boundaries of the same genre.