<![CDATA[Pronunciation is an important component of English language learning because it affects learners' ability to communicate intelligibly. One of the pronunciation aspects that frequently creates difficulties for Indonesian learners is the production of English diphthongs. Unlike Indonesian, English contains several diphthong sounds that require the tongue and lips to move from one vowel position toward another within the same syllable. Differences between the English and Indonesian sound systems may cause learners to substitute, reduce, or incorrectly produce English diphthongs. This study investigates errors in pronouncing English diphthongs among first-grade students of Merangin University. The study employed a descriptive qualitative and quantitative approach. The participants consisted of 25 first-grade university students. Data were collected through an English diphthong pronunciation test consisting of selected English words containing the eight commonly recognized English diphthongs: /eɪ/, /aɪ/, /ɔɪ/, /aʊ/, /oʊ/, /ɪə/, /eə/, and /ʊə/. Students were asked to pronounce the target words individually, and their pronunciation was analyzed based on recorded performances. For purposes of presenting a complete research model, the results reported in this draft use illustrative data. The illustrative findings indicate that the students experienced different levels of difficulty in pronouncing English diphthongs. The greatest difficulties were found in /eə/, /ɪə/, /ʊə/, and /aʊ/, while /eɪ/ and /aɪ/ tended to be produced more accurately. The most frequent types of errors were vowel substitution, monophthongization, inappropriate vowel movement, and inaccurate tongue or lip positioning. The findings suggest that differences between English and Indonesian phonological systems, limited pronunciation practice, spelling pronunciation, and insufficient awareness of English vowel movement may contribute to students' difficulties. The study concludes that systematic pronunciation instruction, listening discrimination activities, phonetic transcription, minimal-pair practice, and repeated oral practice are important for improving students' production of English diphthongs.]]>
