Abstract : Vocabulary is an important part of foreign language learning that must be mastered well by students because vocabulary is an important factor that supports students' ability to communicate. Students who experience little vocabulary mastery will have difficulty understanding English lessons. The objectives of the research is describe the difficulties faced by the eighth grade students of SMPN 6 Kotabumi in the 2021/2022 academic year in mastering vocabulary and describe the dominant difficulties in mastering the vocabulary of the eighth grade students of SMPN 6 Kotabumi in the 2021/2022 academic year. The approach used in this research is qualitative and the method used is case study design. The research was conducted in class VIII SMPN 6 Kotabumi. The data sources of this study were eighth grade students. The data collection techniques were interview, and observation. To analyze the data, the researcher used data reduction, data presentation, and drawing conclusions or verification. The results of this study are the difficulties that students face in mastering vocabulary such as: students are not able to pronounce vocabulary correctly and precisely, students have difficulty in distinguishing vocabulary that has the same spelling and pronunciation, students have difficulty and do not understand grammar and students are unable to understand the context of English. The difficulty most often experienced by students is the lack of understanding of the context in English sentences in all aspects, both in pronunciation, spelling, grammar and grammar..