The strength of diasporic nationalism is characterised by an uneven historical geography, with different diasporic communities functioning as`hotbeds' of nationalism at different times. Mapping and explaining these historical geographies is of importance if the cultural and political experiences of diasporic existence are to be understood. It is towards a critical interrogation of the conceptual tools available to accomplish this task that this paper is dedicated. Based upon a reading of social scienti®c literature on the intensity of national af®liation among the nineteenth and early twentieth century Irish diaspora, and using Doreen Massey's recent advocacy of a new concept of`space±time', the paper advances a case for a (re)theorisation of the phenomenon of diasporic nationalism. In so doing, it is hoped that it will contribute to ongoing efforts to (re)theorise migration in four main ways: ®rstly, by identifying a subject area that provides a forum for population geography researchers to continue their growing dialogue with social and cultural geographers on the one hand and political geographers on the other; secondly, by reviewing the contribution of migration research to work in this area to date; thirdly, by offering a (re)theorisation of diasporic nationalism that places some traditional concerns of population geography at its core; and ®nally, by calling upon migration researchers to engage (once again) with contemporary debates within human geography about time and space, and to re¯ect upon how the conceptions of time and space which inhere within their work, condition the way they de®ne and understand the settlement experiences of migrant groups.