To evaluate the impact of revision--as distinct from other writing enrichment activities such as peer or teacher feedback--on writing skills, two classes of college-bound high school seniors who voluntarily enrolled in a writing course, were given similar instruction in writing evaluation and skill development. While both classes were permitted to do as many drafts of writing assignments as they wished, the "reviser" section was required to revise work nine times. These sections and a third control group (non-college bound seniors enrolled in a conventional class) that had received no special instruction were given pretests and posttests involving prewriting, writing, evaluation, and revision. Results indicated that required formal revision made no significant difference in student writing achievement between the two experimental classes. It did, however, influence student writing habits: those who had been required to revise reported an increased use of revision in other work. The study suggested that formal revision may not have been necessary at this stage of these students' development because of the enrichment training course in evaluation and use of peer feedback, training in audience awareness, etc., before the revision stage. (MM)