Situated at the intersection of sociolinguistic and educational planes, English as a medium-of-instruction debate has always been at the crux of the intense debates, and offers a lens for a systematic investigation of the spread of English in Turkey. As Turkey is moving toward greater integration with the European Union and promoting its competitiveness at the global level, the medium-of-instruction debate is more relevant than ever. Departing from this conceptualization, this state-of-the-art article investigates the medium-of-instruction debate in Turkey by drawing from a wide range of sources including official documents, news articles, and empirical research reports. I contend that the medium-of-instruction pendulum in Turkey is oscillating between national ideas and bilingual ideals, and consequently creates a tremendous influence on social and educational strata of Turkish society. In order to document the swing of the pendulum, the current paper presents a blend of the historical and the sociolinguistic trajectories of the debate and overviews implications in the field of education. The paper concludes with a problematization of existing policies and implementations, and suggests educational policy recommendations that might inform the future of the medium-of-instruction debate and English-language teaching in the formation of twenty-first-century Turkey.