LEXICON Volume 5, Number 2, October 2018, 107-114 Ikhwanuddin Hasan & Aris Munandar / Grammatical Errors | 107 Grammatical Errors Produced by UGM English Department Students Ikhwanuddin Hasan*, Aris Munandar Universitas Gadjah Mada, Indonesia *Email: ikhwanuddinhasan@gmail.com ABSTRACT This research attempts to identify the grammatical errors produced by students of the English Department of UGM year 2012 in their final paper of the writing class. In particular, it attempts to classify the errors based on Surface Strategy Taxonomy proposed by Dulay, Burt, and Krashen (1982). The data used in this research were taken from the submitted assignments of the English Department students of Universitas Gadjah Mada year 2012 in General English, particularly nine students in writing class. We found 178 errors in fourteen linguistic categories which are divided into four parts: omission, addition, misformation, and misordering. From all the four parts, we discovered that the most frequent errors found are in the part of misformation (97 errors; 54.49%), followed by omission (38 errors; 31.11%), misordering (22 errors; 12.78%), and addition (20 errors; 11.11%). However, in the linguistic categories, the three most frequent errors found are misformation of verbal (30 errors), misordering of complex sentence (20 errors), and omission of determiner (19 errors). Keywords: errors, error analysis, grammatical errors, surface strategy taxonomy. INTRODUCTION Since its establishment in 1946, the English Department of Universitas Gadjah Mada (UGM) constantly uses English in its learning activities as the tool of communication between the teachers and the students. However, despite their daily practice, the students of the English Department of UGM still produced errors, especially in writing activity. It is because writing, among the four basic language skills, has more complicated process than the others. A writer needs to think not only the idea that he wants to deliver to the readers but also the right way to express their ideas in a written form. Writing becomes more complex when it is done in academic process. Writing an essay, for instance, deals with some components such as topic and controlling idea, supporting ideas, logical order, cohesion and coherence, and grammatical range and accuracy. Among the five components above, grammatical range and accuracy are considered as the commonest, yet basic problem the students have. Grammar is the essential component in language teaching and learning. Nunan (1999) states, “Grammar is a description of the structure of a language and the way in which linguistic units such as words and phrases are combined to produce sentences in the language.” When the students have a good understanding of grammar system, they are able to construct sentences in an appropriate way. They will also be able to deliver their ideas, messages and feelings to the readers. On the other hand, when the students do not have a good understanding of grammar system, they will find difficulties in constructing sentences. The errors they produce in their writing will cause confusion and misunderstanding among the readers. In 2012, the English Department of UGM has a curriculum with General English as one of the introductory subjects taught in two consecutive semesters while the students are in