This paper aims to reveal the effectiveness of Contextual Teaching and Learning (CTL) approach and Scientific Approach to the teaching of writing skill. This research used a quasi-experimental design. The population was grade VIII students of Redion School. Three classes were randomly selected as the sample. They are class 8A which used the CTL approach, and class 8B which used the scientific approach as the experimental groups, while class 8D became the control group which used the conventional approach. The data were collected by using a writing test. The data were analyzed through descriptive and inferential statistics with the SPSS 20 for Windows computer program. The results were as follows: (1) there were significant differences in the writing achievement among the students taught by using the CTL approach, the scientific approach, and the conventional approach, (2) the use of the scientific approach and the TL approach were more effective than that of the conventional approach to the teaching of writing skill, and (3) the use of the scientific approach was not more effective than that of the CTL approach to the teaching of writing skill. Therefore, the CTL approach and the scientific approach offered the new insights in enhancing the students' writing ability.