The current study explores how integrating a social networking website called Facebook with peer feedback in groups supports student learning, investigates the nature of feedback students received on their writing, and examines their attitudes towards the use of Facebook for peer feedback. The study involves 30 undergraduate students who participated in giving and receiving feedback on Facebook with an aim to develop their writing competence over the fundamental English course of one-semester study. Data were collected from the first and final drafts of writing assignments, written peer comments, a questionnaire and an interview. While the document analysis was the main data collection method, a questionnaire and an interview provided crucial information. The results revealed that the nature of students' feedback focused on content more than grammatical errors. However, quantitative analyses of the peer comments and revisions to the drafts show that feedback given on Facebook had an effect on improving revised drafts. There was statistically significant improvement in the revised drafts which was linked to peer feedback. Finally, the analysis of interviews indicated positive attitude on the use of Facebook for peer feedback in the English class.