Case studies of six college freshmen enrolled in freshman composition courses that used sequenced assignments addressed to the same topic all term were used to investigate how students define revision, how their teachers define it, and what is important about the differences in these definitions. The students possessed a common theory of revision that was thoughtful, consistent, and systematic. It was derived from imagining their readers' process of interpreting what they had written. Viewing prewriting as the primary source of invention, they tended to see revision "externally," to restrict it according to criteria already present in the first draft. Unlike these students, experienced writers--including the teachers in the study--saw revision in a second, "internal" way, as a part of the process of rhetorical invention. Lacking sufficient flexibility, the students had trouble adapting themselves to the teachers' stress on revision as discovery. They tended to misunderstand directions and comments from their teachers intended to suggest internal revision. These results indicated that what the students already knew was blocking what they needed to learn. Their paradigm prevented their teachers' meaning from reaching them. Teachers must recognize the often unpredictable effects of such conflicts, as must composition researchers. (JL)