Researchers have investigated theme-based instruction to guarantee the efficacy of language acquisition and disciplinary content in the modern educational setting. In light of this, this study aimed to examine social science students' perceptions of both the pros and cons of theme-based instruction in their English classes. To address the research issues, I used a combination of quantitative and qualitative methods, such as questionnaires and interviews with 100 social science students at Vietnam National University regarding the use of theme-based learning in the classroom. According to research findings, students' attitudes towards this approach in the course were positive in relation to three key areas: disciplinary knowledge in the social sciences, language acquisition abilities, and learning attitude. Additionally, the research revealed some main challenges students faced when theme-based instruction was implemented in language classrooms, particularly the lack of social science knowledge and the habit of using the mother tongue during class. I hope these findings will serve as the foundation for strategies that best support social science students' English language learning.