Abstract It is a well-known fact that English grammar is at the centre of language acquisition but the approaches that are used in teaching grammar still elicit scholarly controversy. This paper explored and discussed the instructional strategies and their consequent learning outcomes in government seniors schools in Ijebu-Imusin, Ogun State, in particular the strengths and weaknesses of the Grammar-Translation Method (GTM) and the Communicative Language Teaching (CLT) strategy. It employed a qualitative research design relying on the information regarding classroom observations, student assessment, and error analysis in the schools of Saint Anthony Grammar School (SANTOS) and Ikala Comprehensive High School (ICHS). The data was centered on both written and oral performance of the grammar of the students. The results showed that GTM is more likely to develop more structural accuracy in the product of the students but inhibits the process of building communicative competence. On the other hand, CLT encourages oral fluency and often allows the repetition of grammatical errors as unchecked. Students within GTM classrooms demonstrated better results in formal writing assignments whereas their counterparts in CLT-exposed environments demonstrated better results in spoken-based communication situations. The research had a conclusion that neither of the two methods could be used independently to bring about holistic language proficiency. A comprehensive pedagogical approach that would combine explicit structural approach of GTM and interactive and contextual approach of CLT was thus suggested. The teachers are enticed to strike a functional balance between the form-based and meaning-based teaching. It is also recommended to make more comprehensive changes to the curriculum and provide teachers with continuous professional growth to improve the quality of grammar education. The results suggest a significant change in pedagogical practice that should be aimed at providing a hybrid instruction system, which would be responsive to linguistic diversity and need needs of students, and should lead to the enhancement of the overall outcomes in secondary education.