Both in Europe and in other parts of the globe ethno-religious diasporas constituted major actors in pre-modern long-distance trade. The project studies three relationships between ethno-religious diasporas and long-distance trade: First, it explores the hypothesis that diasporas created self-enforcing institutions that ensured fulfilment of informal contracts between business partners. Second, it follows a Weberian tradition in studying connections between the social and cultural characteristics of a diaspora and the business practices of merchants belonging to that particular group. The third avenue of inquiry relates to long-run cultural secularization in that it investigates the ways in which the formalization of contractual relationships in business transactions created inclusive markets and thereby weakened the role of diasporas in long-distance trade. The study draws its empirical material mainly from the European and Atlantic worlds of the 15th to 19th centuries. Apart from a synthesis of existing research in view of the three relationships mentioned above the project carries out original research on Jewish communities in eighteenth-century Germany, particularly with respect to their role in the organization of minting and the associated bullion trade.