Felani Wayan Rici Rasti Pengarang Prof. Drs. Tans Feliks, M.Ed., Ph.D Dosen Pembimbing 1 Tans Feliks Ketua Penguji Sebastianus Fernandez Penguji 1

This study deals with the analysis of types and the most dominant types of interferences found in English essays written by Indonesian students of English Department. It involved 23 fourth-semester students of the English Department, University of Nusa Cendana, who enrolled in Academic Writing class. The approach applied in this study was descriptive qualitative. The data were gathered from the students’ essays in the academic year 2016/2017. The findings of this study showed that students made three types of interferences namely lexical interferences, morphological and syntactical interferences. Lexical interference fell into two categories: literal translation at level of word and literal translation of first language preposition. Morphological interference fell into two categories: (1) Interference in forming plural nouns. (2) Error in applying the inflection of verbs. Syntactical interference also fell into four categories omission in applying the articles, errors in applying auxiliary verbs, errors in translating pronoun as an object, omission of auxiliary verb (do/does), and error in applying conjunction. The most dominant types of interferences made by students are syntactical interferences which have 46.3% from all types of interferences that have been found. Keywords: interference, Essay