Abstrak
The purpose of this study was to assess the types of grammatical errors and the most common grammatical errors made by seventh-grade students in SMPN 5 Tarakan in writing descriptive text. The subjects of this study were 30 seventh-grade students. The data were collected by asking the students to write a descriptive text on the given topics. The data were analyzed using statistics and descriptive analysis. The result of the study showed that there were sixteen grammatical errors, namely verb to be, determiner, subject verb agreement, plural, singular, word order, word missing, unnecessary, conjunction, spelling, article, pronoun, possessive, noun, preposition, and gerund. Thus, the most common grammatical errors made by the seventh grade students of SMPN 5 Tarakan in writing descriptive text was Spelling with the percentage of 22.2%. Therefore, it can be concluded that the students faced problems in the process of writing a text such as having low knowledge about how to write a text using grammar correctly.