This study discusses content-based instruction in writing. The purposes of this study are to find out its application in teaching writing, its influence on writing outcomes, and students' motivation in writing. This study was conducted on grade VIII students' of Junior High School 6 Wasile, located in North Maluku province. The method used in this study is a quantitative method with three instruments, namely a test consisting of a pre-test and post-test, an observation composed of an observation checklist for teacher an observation checklist for students', and a questionnaire instrument containing questions for students'. The data obtained in this study were analyzed quantitatively using the SPSS application. The result shows that the application of content-based instruction in teaching writing skills is applied well and meets the aspects of the observations made. From observations, it is also known that the application of content-based instruction makes students' react positively to the learning by application well as long as teaching process. Then, the use of content­based instruction impacts students' writing skills, which is marked by a significant improvement in scores in the experimental class that treated using content-based instruction. As a comparison, the control class taught using a conventional method tends not to experience a significant improvement in scores. It can be scientifically confirmed that content-based instruction impacts students' learning outcomes in writing skills. Beside that, it is gives students' motivation for learning writing skill. The results of the questionnaire also showed that students' showed more positive attitudes and were more interested when teachers used content-based instruction in their learning. So, it can be said that content-based instruction can be improve students' motivation to learn writing skills.