This paper focuses on the commercial exploitation of ethnic diaspora-based networks. Using qualitative data from four London minority-owned enterprises, diaspora-based linkages in the UK and beyond are examined and the implications for policy discussed. We conclude that, under certain conditions, diaspora-based networks enable higher levels of business competitiveness. They facilitate access to resources and markets by minorityowned businesses, particularly for those supplying ethnic goods and services,. Exploiting diaspora-based networks effectively depends not only on business owners' capabilities and motivations to do so but also on diaspora structures*their size, geographical and sectoral locations*and the resources and opportunities they make available to business owners. Conversely, in certain circumstances, engagement with diaspora-based networks can constrain business competitiveness, particularly where this restricts the resources and markets available. Diaspora-based networks are potentially important influences on business competitiveness but do not negate the importance of class resources such as property, education and skills in processes of business formation and development among minority groups. The implications for existing theory and for policy are considered.