The article reports on the results of a research project carried out by the Sociology of Development Research Centre, University of Bielefeld. Starting from the observation that trade in Southeast Asia is commonly carried out either by ethnic minorities or by women, several intensive and long-term field studies were conducted in Thailand, Singapore, and Indonesia. The studies concentrated on Chettiar money-lenders and traders in traditional Chinese products in Singapore, rice traders in Central Thailand, the Thai-Malaysian border trade, and Nepalese groups trading with Southeast Asia. On the basis of the research findings several hypotheses on the emergence and role of trading minorities in Southeast Asia are compared and evaluated. The "traders’ dilemma hypothesis", stressing the strategic use of cultural differences between traders and customers, was pin-pointed as the most viable explanatory paradigm.