Administering English language teaching (ELT) in rural settings of the three southern border provinces has been challenging for both teachers and learners due to two decades of political unrest, eruptions of violence, fears, and insecurity. To enhance ELT, this study aimed to investigate factors affecting the ineffectiveness of ELT in these three educational environments and introduce a new lens of contextualized English instructions for learners in schools located in Southernmost Thailand, where learners live amid linguistic and cultural diversity. In this qualitative study, data were collected from teachers operating in two schools of each province (totaling six institutions) by semi-structured interviews and analyzed by content analysis. Findings revealed that five primary factors deteriorating English language learning efficiency in the three southern border provinces were Implementation of Broad-Spectrum ELT Policies; Insufficient Teaching Integrations with Islamization; Inadequate Awareness of the Significance of English; Inconsistencies between ELT Textbooks and the Sociolinguistic Reality of English; and Impractical Classroom Arrangement. The findings could be beneficial if they are further utilized by the Ministry of Education in establishing policies for ELT in specific contexts as well as school administrators and teachers in formulating instructional approaches, managing learning resources, and arranging classrooms based on local needs and identities. Although this study has a specific spatial scope, which is the three southern border provinces of Thailand, its findings can be adapted for a broader application as a part of the global perspective and a clue to solve language learning problems across ELT communities encountering a similar challenge.