Singapore's remarkable performance in Programme for International Student Assessment (PISA) has placed it among the world's high-performing education systems (HPES). In the literature on HPES, its "secret formula" for education success is explained in terms of teacher quality, school leadership, system characteristics and educational reform. This article offers an alternative explanation for the education success of Singapore and, in so doing, questions the basic assertions of the HPES literature and, in particularly, the use of PISA results as the prime indicator of the educational performance of a school system. The explanation is informed by a historical perspective on the development of the Singapore education system and based upon a body of empirical findings on the nature of pedagogical practice in classrooms, both of which are vital for understanding the educational performance of Singapore's education system. The article concludes by addressing the implications of this analysis for educational policy borrowing.