ABSTRACT EliNofriati.2016 Improving students’ Essay Writing Ability Throughthe Implementation of Semantic Mapping Technique. (A Classroom Action Research at the fourth Semester students of English Department of Almuslim University, Matangglumpangdua, Bireuen). Thesis.Graduated Program in English Language Education. State University of Syiah Kuala. Advisors: (I) Abdul Gani Asyik, M.A., Ph.D. (II) Dr. Bukhari Daud, M.Ed. Keywords: Semantic Mapping Technique, Essay Writing The objective of the research was to improve students’ essay writing ability through Semantic Mapping technique. This research belongs to a classroom action research design in which the researcher and observer work together in designing the lesson plan, implementing the action and making reflection. The subjects of the research were all the fourth semester students in Unit A at English Department of Almuslim University, Matangglumpangdua, Bireuen. The subject consisted of 34 students. The study was conducted in two cycles by following the procedure of the action research, they were: planning, implementing, observing, and reflecting. In collecting the data, the researcher used some research instruments, such as: observation checklist, test, questionnaire and field note. The obtained data were presented and analyzed in qualitative and quantitative data. The findings of the research showed that the implementation of semantic mapping technique in essay writing class was effective and could motivate the students in learning essay writing. The researcher found the percentage of the researcher’s performance in implementing Semantic Mapping technique in teaching essay writing in the first cycle was 75.3% and it was improved to 88.3% in the second cycle. Meanwhile, the percentage of the students’ activities during learning process in the first cycle was 57.3% and rose to be 79.3% in the second cycle. Further, the researcher also found that the result of the students mean score of writing test in cycle 1 was 59.64 and it increased become 75.85 in cycle 2. The other result also found by the researcher from the questionnaire, it was found that the students’ responses toward the implementation of Semantic Mapping technique in teaching essay writing was 4.62 or in category “strongly agree”. It means that the students gave good and positive responses. In conclusion, the researcher could conclude that the use of Semantic Mapping technique could improve the students’ ability in learning essay writing and could solve the students’ and lecturer’s problem in teaching and learning essay writing class and it means that the research had done successfully.