2.000). Ini berarti bahwa hipotesis nol (Ho) ditolak dan hipotesis penelitian (H1) diterima. Kesimpulan dari penelitian ini adalah ada pengaruh positif dari penerapan metode Kooperatif terhadap prestasi menulis siswa daripada siswa yang menggunakan metode Terjemahan Tata Bahasa (GTM) pada siswa kelas 1 SMA N 1 Kramat Kabupaten Tegal Tahun Akademik 2009/2010. Inggris : NUR ROHMIATI. 2010. 1606501537. "The Effectiveness of Cooperative Learning toward Students' Writing Achievement of the First Year Students of SMA N 1 Kramat (An Experimental Study at SMA N 1 Kramat, Tegal Regency in Academic Year 2009/2010)". Thesis. Strata 1 Program, Faculty of Educational and Teaching Training, Pancasakti University Tegal. Key words : Effectiveness, Cooperative Learning Method and Writing Achievement The objective of the research is to know whether there is any positive effect of Cooperative Learning method application on the first year students' writing achievement in SMA N 1 Kramat, Tegal Regency in Academic Year 2009/2010. Based on the review of related theory and the logical framework, the hypothesis of this research is: there is a positive effect of the Cooperative Learning method application toward students' writing achievement than those who use Grammar Translation Method (GTM) on the first year students of SMA N 1 Kramat- Tegal Regency in Academic Year 2009/2010. The population of this research is all of first year students on second semester at SMA N 1 Kramat, in Academic year 2009/2010. The number of population is 364 students from 9 classes. The writer uses 60 students as the sample from the first year students. The first group is experiment group which contains 30 students and the second is control group which also contains 30 students. The two groups are taught by using the same material but the different in method of teaching. The experiment group is the students who are taught by using Cooperative Learning and the control group is the students who are taught by using Grammar Translation Method (GTM). Then both of them given the same writing test. The writer uses a writing test as the instrument of the research. The type of the test is an essay test. From of an essay test students must be able to make descriptive text for about 2 paragraphs. The data of this research is gained from the writing test that was given to the sample of this research. To analyze the data, the writer used t-test to know the difference between the two groups. Based the data analysis, t-ratio is 14.078 with the degree of freedom (df) is 58 on the level of significance (?) 5% and the t-table is 1.645. It means that the t-ratio is higher than the t-table (14.078 > 1.645). It means that the null hypothesis (Ho) is rejected and the hypothesis of the research (H1) is accepted. The conclusion of this research is there is a positive effect of Cooperative Learning Method application toward students'writing achievement than those who use Grammar Translation Method (GTM) on the first year students of SMA N 1 Kramat Tegal Regency in Academic Year 2009/2010." />