This paper seeks to introduce this special issue by setting out what seem to be some of the major theoretical and methodological issues raised for comparative education by the increasing prominence of the discourses of the knowledge economy, which, it is argued, represent a particularly strong version of globalisation and its possible relationships to education systems, and hence an especially acute challenge to comparative education. It focuses on the possible implications of these changes for each of the three elements of national education system. In terms of the it discusses the nature and consequences of methodological nationalism, and emphasises the emerging pluri-scalar nature of the governance of education. In terms of education, it argues that education is now being asked to do different things in different ways, rather than the same things in different ways. In terms of system, it is suggested that the constitution of education sectors may be in the process of changing, with a development of parallel sectors at different scales with different responsibilities. Overall, the article suggests that we may be witnessing the development of a new functional, scalar and sectoral (non zero sum) division of the labour of educational governance. Finally, it addresses the question what is now to be compared and considers the consequences for both explaining and learning through comparative education.