This study examined the effects of peer feedback combined with teacher feedback on L2 writing. From a review of related studies, several factors were selected as predictors of L2 writing proficiency: L2 knowledge and composition skills, L2writing anxiety, and metacognitive knowledge on L2 writing. Participants were 75college students, who were randomly assigned to the experimental or the control group. Both groups received teacher feedback, while the experimental group performed peer feedback activities, and the control group did self-reflective revision in addition. Data were collected from teacher and peer feedback, timed writing, an L2writing anxiety survey, and evaluation of a sample essay. A statistical analysis revealed differences between teacher and peer feedback. Peer feedback combined with teacher feedback appeared to be beneficial for increasing L2 knowledge and lowering L2 writing anxiety. In the regression analysis, writing anxiety predicted the level of L2 knowledge and composition skills. Based on the findings, implications for L2 writing class and suggestions for future studies are presented.