This study evaluated the effect of the teaching cycle adapted from the genre-based approach for teaching EFL learners in Thailand. As English writing is claimed to be the most serious problem among Thai EFL learners, the instruction aimed at developing writing competence of Thai EFL learners. One-group pretest-posttest design was employed in the study. The participants were 44 undergraduate students enrolling in a course of English writing for English teachers. This 12 week course aimed at teaching writing in the news report genre. After completing the course, two sets of tests were administered to measure their writing developments. The first test measured the students' development in linguistic features. The second test evaluated the students' performance in a writing task. A semi-structured interview was used to show students' attitudes towards the instruction. Quantitative results showed students made greater improvement in linguistic features and rhetoric organization, the majority of the students gained development at 'Moderately Improved' level. Qualitative results indicated students expressed positive attitudes towards autonomous and explicit learning. The students reflected that collaborative writing helped to improve their writing competence and increased their confidence in composing texts. The study concluded by stating the effectiveness of a genre-based approach to the development of EFL writing competence.