Agus Mulyana Ketua Penguji Nirna Nirmala Penguji 1 Hery Nuraini Dosen Pembimbing 2 Achmad Fachrurrozy Penguji 1 Marisa Afti Mutia Pengarang

The aim of this research was to know whether there is a significant effect of self-efficacy on writing skill. Also to determine which one is dominant between self-efficacy and writing skill. This research is quantitative design, 30 students as the sample which taken non-random by using quasi experimental research with one group. Students’ test and questionnaire was used by the writer to collect data. The hypothesis data was using Wilcoxon Non-Parametric with one sample. It was known that Test Statistic' Asymp.sig (2-tailed) worth 0.000 smaller < 0.005. It can be concluded that "Ha is accepted". There is a difference between a student's writing skills at the time of pre-test and post-test. So it can also be concluded that there is an effect of writing self-efficacy intervention on writing skills at the tenth grade at SMAN 14 Kota Tangerang. Then, it was also known from the percentages students’ post test 100% can pass writing skill. Moreover, students’ self-efficacy intervention was good with the percentages 63,44%. Keyword: Writing Skill, Self-Efficacy Intervention