Grammar plays an important role in EFL writing. However, many first-year students struggle with grammatical accuracy due to various factors. This study aims to identify common grammatical errors in English paragraph writing among first-year English majors at Nam Can Tho University in the Mekong Delta by analyzing sixty students’ written paragraphs. Moreover, semi-structured interviews were conducted with five students who made the most grammatical errors to gain insight into their perspectives on the causes of the errors. The findings indicated that students frequently made errors related to collocations (32.95%), word form (17.90%), prepositions (15.63%), subject-verb agreement (9.09%), sentence structure (9.09%), omission of “to be” (8.52%), verb tense (3.98%), and articles (2.84%). Among these errors, word form and collocations were considered to have the most significant impact on their ability to express an idea clearly. The interview results revealed that the main causes of these errors were reported to be mother tongue interference, lack of grammar knowledge and practice, lack of proofreading skills and time constraints. Article visualizations:
Huyen et al. (Tue,) studied this question.