Karolus B. Siga Pengarang NOVRIANI RABEKA MANAFE Dosen Pembimbing 1 MARCELINUS YERI FERNANDEZ AKOLI Dosen Pembimbing 2 Joseph Bhisara Kroon Ketua Penguji Novriani Rabeka Manafe Penguji 1 Marcelinus Yeri Fernandez Akoli Penguji 2

This research aimed to discuss the first language interference on students' speaking activities at the English education department of Nusa Cendana University. The purpose of the study is to find out the types of interference and the factors that cause interference. The writer focused on students’ speaking activities. The writer used a qualitative method. Data were collected from observation and interviews. The writer selected some words or sentences that included interference by using Weinreich's theory and analyzed them. As a result of the research, the writer found that most students do the interfere. Therefore, the writer concluded that interference occurs in linguistic aspects, namely: phonological, grammatical, and lexical interference. Moreover, the imperfect learning, mother tongue transfer, and the limited vocabulary of the target language mastered are the major factors causing the interference by the learners. It shows that there are many errors due to language interference that influence bilingual speech. Keywords: First language, Interference, Speaking.