The problem is “how can the use of Theme-based Approach improve students’ writing skill?” and the objective of this research referring to the research problem is to improve the seventh grade students’ writing skill through Theme-Based Approach. The design of this research is classroom action research. The research subject is VII E class consisting of 36 students. The data are collected using interview, observation, test and instrument used is test items. In order to analyze the data students’ writing score-, percentage formula is used. Theme-Based Approach improved the students’ writing skill in two cycles percentage of students scored ≥70 was 63.8% in the first cycle, and it was 77.7% in the second cycle. Based on the research result, it can be concluded that Theme-Based Approach is able to improve writing skill at SMP Negeri 2 Bangorejo in the 2015 – 2016 academic year.