In the study of religion, Ninian Smart and Kim Knott were among the first to make a plea to investigate 'ethnic minority' or 'migrant' religion, and to indicate trends and patterns. In the 1990s a gradual vocabulary shift, from 'migration' to 'diaspora,' took place, at least in religious studies. Diaspora communities have increasingly become visible in public life, and their places of worship have begun to be recognisable features of the religious mosaic in many European cities. This special issue on Hindu ritual dynamics in western Europe starts with an introductory essay on some of the basic expressions used in the descriptions and analyses by the various authors. The introduction gives the reader a first impression of the ritual space that Hindu communities in the United Kingdom, the Netherlands, Norway, and Switzerland are occupying today.