This study investigates the characteristics and effectiveness of peer revision on second language writing as an aid to teacher feedback. It compares peer revision with the individual revision, helping analyze the former in a more controlled way in terms of its general usefulness. The study was conducted at Middle East Technical University. The data was collected through peer revision processes, in which peers reviewed each other’s writing, and through think-aloud protocols, which involve students reviewing their own writing. The participants were 10 advanced level students enrolled in a composition class. Qualitative and quantitative data analysis techniques were employed in the analysis and the type of interaction among the peers was identified. First and second drafts written before and after the peer revision and before and after the individual revision were compared. The processes of peer and individual revision were also compared. Additionally, the researcher proposed changes in essays and compared them with peer-proposed changes and individual changes. The texts were compared with respect to nine categories: vocabulary, grammar, spelling, punctuation, morphology, syntax, preposition, correlation of ideas, and organization. The results indicate that peer revision is a worthwhile activity regardless of whether it leads to highly successful revisions. Texts showed notable differences in eight categories. When students were included in peer revision, they made more changes than they did in individual revisions. The data showed that peers do have the competence to provide useful comments on each other’s writing, and that peer revision can lead to language learning.