Writing is a long process; therefore, students need to do some steps to write, beginning from the considerations of choosing a good topic till writing a final copy, includedto review and to revise again and again, from time to time. Peer and self editing strategies are social and metacognitive strategies used in the steps of sharing, revising, and editing in writing. The aim of writing this article is to see how peer and self editing strategies are able to improve students’ writing skill. Classroom action research design was used and 64 students were taken as subjects of the research. The instruments used were peer editing worksheet, self editing worksheet, and test sheet. Data analysis method used was based on the procedures of planning, acting, observing, and reflecting phases. The research results showed that there were improvementsin all elements of writing: the quality of format, punctuation and mechanics, content, organization, and grammar and sentence structure.Based on the research results shown and the criteria of success determined, it can be concluded that peer and self editing strategies are able to improve students’ writing skill.