This research aimed to describe the types of grammatical overgeneralization and
find out causes how such overgeneralization happen among the students. This
research used a qualitative descriptive method using students’ writing assignments
as the data source. The theory of Surface Strategy Taxonomy was used in the data
analysis by describing the errors. There were 33 participants from the 4th semester
students of English Department at UIN Antasari Banjarmasin who were recruited
through purposive sampling. This research found four types of errors, with a total
of 77 errors, including 20 errors of omission, 17 errors of addition, 33 errors of
misformation and 7 errors of misordering. Meanwhile, two causes of errors were
found: interlingual transfer 27 times and intralingual transfer 50 times. After
conducting this research, there are several suggestions provide to the lecturers and
the students. The lecturers must pay attention to the students’ errors by
underlining them and asking the students to fix that error with correct grammar.
The students should apply and improve the knowledge related to English grammar
for minimize or even not make errors in writing English texts