The aim of this research was to find out the effectiveness of Know-Want- Learn (KWL) technique for teaching writing at the second grade students in one of junior high schools in Cilacap in academic year 2013/2014. This research used quasi experimental research which was conducted on 1st until 30th April 2014. The sample of this research was 31 students from D class as an experimental group and 31 students from A class as a control group. The instrument of collecting the data was test. The test was done twice, they were pre-test and post-test. The type of the test was essay. T-test formula was used to analyze the data. Based on the computation, t-test result was 4.93 and t-table was 1.671 at the significant level 0.05 with the degree of freedom 60. It showed that t-result was higher than t-table (4.93>1.671). KWL technique was effective to develop students’ competence of writing aspects because it could activate the students’ prior knowledge. This technique provided a structure for recalling what students knew about a topic, noting what they wanted to know, and finally listing what had been learned. It offered a framework for the students to be easier in writing a text. Based on the research result, it was concluded that the KWL technique was effective for teaching writing narrative.