The materials and the energy flowing through a city satisfy human needs and their flows are driven by the demand generated by the activities which serve to satisfy these needs. The aim of this project is to understand the how the practices in which these activities are embedded are formed, reproduced and changed through history and how they differ depending on the context. By linking elements of the theory of social change, sociotechnological change and industrial ecology, a model is developed of how practices are formed in an interconnected individual, social and technological world, and which can potentially explain the patterns and trajectories observed in the formation of practices. Such a systemic understanding of the drivers of the urban metabolism should shed light on the origin of different metabolic patterns across cities and time. Such knowledge could be of use for policy intervention, by facilitating the intervention at the cause, rather than at the level of the symptom, and by identifying interrelations which might interfere with the implementation of any intervention.