This study went through over 1,600 marginal and end comment written on 110 drafts of essay by 47 university ESL advanced student, considering both the pragmatic goals and the linguistic features of each comment. Drafts of individual essays were examined to observe the influence of the first draft commentary on the student revisions and assess whether the changes that were made in response to the teacher´s feedback improve the essays. A significant proportion of comments led to substantive student revision, and there were types and forms of commentary were more helpful than other commentaries. Final results are suggestive of several implications for L2 writing instruction and for studies on a vital but neglected topic.