The aim of this research was to describe the implementation of cooperative learning in teaching writing of MTs Al Ishlah Pageruyung, Kendal. Cooperative learning essentially involves students learning from each other in group. It is known to provide positive interdependence support on student group members in enhancing learner achievement, interaction, motivation and productivity their writing skills, therefore the researcher of this study intend to further investigate how CL provides knowledge that is responsible for developing writing skill by answering the following research question. The students of junior high school are the intermediate level after the beginner level (Elementary school) of study. In the junior high school is the golden age to release the rule of language. Different level of study must have different treatment. It should be suitable objective of the learning. For suitable treatment of the learning, so it needs current method of teaching. This qualitative research has purpose to describe the implementation of cooperative learning in teaching writing. To obtain the data, qualitative research method the researcher used observations interviews and documentation. The English teacher of the seventh grade of MTs Al Al Ishlah Pageruyung, Kendal, who agreed to participate in the research. The results of this study showed that the implementation of cooperative learning teaching writing was believed to be effective to enhance learner achievement, interaction, motivation, and productivity in writing.