This article investigates the urban and economic revitalisation of a traditional industrial working-class neighbourhood into a knowledge-based economic district. It explores why and how this new district is the result of an assertive public policy led by Barcelona's city council and implemented by a quasi-public agency. The project represents the most important urban-growth strategy in the city at the turn of the century and also exemplifies the advantages and shortcomings of many of the policy elements that have contributed to the radical transformation of Barcelona in recent decades. The article further highlights methodological challenges regarding the conceptualisation and operationalisation of new economic activities and it discusses the spatial and uncertain economic consequences of this ambitious approach by the local government. © 2009 Urban Studies Journal Limited.