Abstract
This study investigates the impact of Interactive Grammar-Based Teaching (IGBT) on concord comprehension and self-confidence among tertiary-level ESL learners. A single-group quasi-experimental design was employed, using pre-test and post-test measures to assess changes in learners’ grammatical competence and self-assurance in English language usage. The participants were tertiary-level ESL learners from a specific university, and the instructional intervention focused on interactive grammar activities targeting subject-verb agreement. Data were analyzed using descriptive statistics and paired-sample t-tests. Results indicated a significant improvement in both concord comprehension and learners’ self-confidence after the IGBT intervention. Despite these promising findings, the study has single-group design, restricted sample, and short duration of intervention, which may affect generalizability. The findings underscore the importance of interactive and learner-centered grammar instruction in tertiary ESL contexts and provide implications for future research and pedagogical practice.