Ayu Matni Pitronela Bonat Pengarang NOVRIANI RABEKA MANAFE Dosen Pembimbing 1 DEWI I N BILI BORA Dosen Pembimbing 2 Novriani Rabeka Manafe Ketua Penguji Gracia M. N. Otta Penguji 2 Dewi I N Bili Bora Penguji 1

The title of this research is “Language Interference in Learning English of 7th Grade Students at SMPTK Imanuel Tuapakas in South Central Timor Regency”. The aims of this research are: (1) to find out the types of language interference in learning English, (2) to find out the most dominant example of the mother tongue in learning English, and (3) to find out the causes of interference in learning English. The research design of this research was a descriptive qualitative method in this study the writer selected twenty students from seventh grade. This research used observation, document analysis, interview, note-taking, and data analysis to collect the data and to answer the researcher's questions. The researcher used three main steps (1) observation (2) interview (3) documentation. From the self-introduction by the seventh-grade students, the researcher found that there were three types of language interference made by seventh-grade students. The types were phonological, grammatical, and lexical interference. The researcher also found the most dominant example of the mother tongue in learning English made by seventh-grade students is phonological interference. The researcher also found the causes of language interference, there were students’ background and the students’ limited mastery of the English vocabulary. Keywords: Language Interference, Mother Tongue, SMPTK Imanuel Tuapakas