The purpose of this study is to describe the negotiations that occur during ESL students' peer reviews and the ways these negotiations shape students' revision activities. Twelve advanced ESL learners enrolled in a writing course participated in peer reviews. Audiotaped transcripts of the peer reviews and the students' first and revised drafts were analyzed, and postinterviews were conducted. During these peer reviews, students asked questions, offered explanations, gave suggestions, restated what their peers had written or said, and corrected grammar mistakes. Reviewers generated most types of negotiations. Moreover, certain patterns of negotiations occurred more frequently in peer dyads from different fields of study than in dyads from the same field. Although students used their peers' comments to revise their essays, they incorporated those comments in their revisions selectively, deciding for themselves what to revise in their own texts. Finally, the postinterviews supported students' rationale for their revision activities and revealed that overall they found peer reviews useful. The findings of this study support the need to include peer reviews in L2 writing instruction and underscore their value in providing feedback on students' essays.