Background and Aim: The adoption of English Medium Instruction (EMI) in Thailand, particularly in university-level international programs, was driven by various factors. Most notably, it was viewed as a strategic move to prepare students for an increasingly interconnected world where English reigns supreme in academia, business, and diplomacy. This research examines the attitudes, challenges, and practices of English Medium Instruction (EMI) in an international program at a Thai university from the perspectives of Thai EFL learners. Materials and Methods: The study employs a mixed-methods approach, utilizing surveys, interviews, and classroom observations. A five-point rating scale questionnaire was distributed to 80 learners to investigate their perceptions of EMI. Additionally, in-depth interviews were conducted with 8 participants to gather detailed information on their attitudes, perceived advantages, and challenges related to EMI. Results: The findings reveal that Thai EFL learners have a positive attitude towards EMI, recognizing its benefits for English language proficiency and future employment opportunities. However, they face challenges in understanding instructors' English speaking, comprehending materials, and acquiring specialized vocabulary. Conclusion: The study emphasizes the importance of language preparatory courses, provision of support materials, teacher training, and the development of intercultural competence. Furthermore, it suggests that future research should involve a larger sample size and encompass various educational environments to gain a comprehensive understanding of Thai EFL learners' perspectives on EMI in international programs at Thai universities.