ABSTRAKThis research aims to (1) analyze to what extent NHT technique can improvestudents’ skill to write descriptive texts; (2) describe to what extent NHT techniquecan improve classroom effectiveness.This action research study was carried out at SMP Negeri 16 Surakarta for 24students of class VIII C. It was conducted in two cycles. Each cycle consisted of:planning, acting, observing, and reflecting. The qualitative data were collectedthrough observation, interview, questionnaire, and diary; whereas the quantitativedata were collected by conducting test.The result of this research shows that (1) the implementation of NHT couldimprove students’ skill to write descriptive texts. The improvement of students’achievement in writing descriptive text was viewed from the improvement ofstudents’ mean score.  The mean score of writing test increased from 58.41 in thepre-test, 68.58 in test 1, and 74.91 in the post-test. (2) The implementation of NHTcould improve classroom effectiveness. The improvement of classroom effectivenessincluded: a) students were more motivated in learning English; b) students paid fullattention to the teacher; c) students were more interested and eager joining thelesson; d) students focus on the lesson and discussion; and e) students were moreactive in discussion and participate to the lesson.  NHT technique is an alternative teaching technique that benefits both forstudents’ achievement and for the classroom effectiveness. As the suggestion, theteacher should consider NHT technique as an interesting and appropriate techniqueto teach language. Based on such findings as presented above, it is also hoped thatNHT technique can be implemented in teaching other English skill.Keywords: writing skill, descriptive text, Numbered Heads Together technique,classroom action research