The research project entitled 'Metabolic Impact Assessment: from concept to practice' brings together two separate research fields, Urban Metabolism and Strategic Environmental Assessment. The main objective is to further work on the concept of Metabolic Impact Assessment (MIA) to make it operational and readily applicable as a new, innovative and far-reaching planning policy instrument, able to improve the metabolic efficiency of our cities and metropolis. Departing from the rich and diversified research carried out on modelling of urban metabolism, the principal idea behind MIA has been to conceive a methodology that is able to estimate the impact of new planning proposals such as urban plans and major urban development projects on the existing metabolic performance of cities and metropolis. MIA has been initially conceptualised as a potential decision making tool able to feed the development control process, taking advantage of the comprehensive and holistic view of cities provided by urban metabolism models. However, the first application of MIA, albeit producing very interesting and promising results, has also revealed two major barriers: one related with the methodological complexity and data demanding nature of MIA and, the other, related with the need to provide MIA with a solid procedural framework, incorporating the MIA concept into existing Strategic Environmental Assessment (SEA) procedures, otherwise this promising idea would never get full recognition and wider dissemination in the professional worlds of impact assessment and urban planning and management. To address these barriers, making the MIA concept truly operational, two main research challenges are open ahead and will be explored in this research project, one following an institutional/procedural perspective (based on the idea of a kind of 'plug-in' solution to articulate MIA with the existing SEA procedures without significantly changing these, which would certainly constitute an additional political and administrative obstacle to the wider acceptance of this new and innovative concept) and, the other, following a methodological/technical perspective (with focus on how approaches to urban metabolism modelling can be simplified and made less data demanding and user friendly within the context and for the specific purposes of MIA applications to urban projects).