After sketching in the background for conversation generally about theoretical and methodological issues in comparative education and more specifically about its historical dimension, the author seeks to identify theories that, despite widespread eclecticism and even support for atheoretical standpoints, appear influential, together with characteristic forms of historical analysis. With these preliminaries as a basis, he analyses strategies for clarifying the historical dimension. This leads him to focus both on the units/levels of comparison and on three structures that can be used for this purpose: the familiar (narrative) forms of diachronic analysis, the more in-depth approaches opened up by synchronic analysis, and hybrid forms. The article also recognizes and explores problems associated with the use of the historical dimension, emphasizing those related to sources, interpretation, and periodization, while illustrating these problems and their possible solutions with specific examples from Hong Kong and elsewhere in the world. The article concludes by reaffirming the importance of the historical dimension of comparative education. [Copyright of Comparative Education is the property of Routledge. Full article may be available at the publisher's website: http://dx.doi.org/10.1080/03050060500073231]