Abstract :
This study aims to identify the types of grammatical errors and analyze the sources of grammatical errors committed by students in writing cause-and-effect paragraphs. The types of errors were analyzed based on surface strategy taxonomy by Dulay, Burt, and Krashen (1982), and the sources of the errors were analyzed through theory by Brown (2000). This research used a mixed-method design as the research design. The data was collected through document collection of final tests. The subjects of this study were students in two classes of the English Language Education Program in the second semester of the 2020/2021 academic year. The results of this study showed that the types of grammatical errors in students' writing from the highest to the lowest based on Dulay's theory are divided into four categories. The highest types of errors were omissions errors with a total of 54 errors or 44%, misformation errors with a total of 37 errors or 31%, addition errors with a total of 28 errors or 23%, and misordering errors with a total of 3 errors or 2%. The total errors committed by students in their paragraph writing were 122 errors. Based on all of these types of errors, the researcher conducted an analysis of the source of errors and found that the source of errors in students' writing was caused by intralingual transfer 82 or 67%, interlingual transfer 35 or 29%, and communication strategies 5 or 4%.