ENGLISH :
This research investigated the pronunciation errors made by eighth-grade students at SMPN 5 Mendo Barat in articulating English consonant sounds that do not exist in their first language. The study involved 20 respondents who were given a pronunciation test consisting of six targeted consonant sounds: the labiodental fricatives (/f/, /v/), the dental fricatives (/θ/, /ð/), and the palato-alveolar affricate (/ʤ/). The purpose of this study was to identify the types and frequency of errors made by students and to analyze the influence of the first language on their pronunciation. The analysis revealed that the errors were mostly in the form of substitution, omission, and misordering. Consonant sounds such as /f/ was frequently replaced with /p/, /v/ with /f/ or /p/, /ð/ and /θ/ with /t/ or /d/, and /ʤ/ with /g/ or simplified. A total of 206 errors were recorded. The highest error occurred in the voiced dental fricative /ð/ (28,2%), followed by /f/ (19,9%), /ʤ/ (18,4%), and /v/ (18%), and /θ/ represented the lowest percentage with (15,5%) of errors. These findings suggest that Indonesian learners experience significant challenges in pronouncing English consonant sounds that differ from their first language, with first language interference playing a major role in shaping their pronunciation errors.