In Architectures of Knowledge, Ash Amin and Patrick Cohendet argue that the time is right for research to explore the relationship between two other dimensions of knowledge in order to explain the innovative performance of firms: between knowledge that is 'possessed' and knowledge that is 'practiced' generally within communities of like-minded employees in a firm. The impetus behind this argument is both conceptual and empirical. Conceptually, there is a need to explore the interaction of knowledge that firms possess in the form of established competencies of stored memory, with the knowing that occurs in distributed communities through the conscious and unconscious acts of social interaction. Empirically, the impetus comes from the challenge faced by firms to the hierarchically defined architecture that bring together specialized units of ((possessed)) knowledge and the distributed and always unstable architecture of knowledge that draws on the continuously changing capacity of interpretation among actors. In this book, these questions of the dynamics of innovating/learning through practices of knowing, and the management of the interface between transactional and knowledge imperatives, are approached in a cross-disciplinary and empirically grounded manner. The book is the synthesis of an innovative encounter between a socio-spatial theorist and an economist. The book results from the delicate interplay between two very different epistemologies and consequent positions, but which progressively converged towards what is hoped to be a novel vision. The book begins by explaining why knowledge is becoming more of a core element of the value- generating process in the economy, then juxtaposes the economic and cognitive theorization's of knowledge in firms with pragmatic and socially grounded theorization's and a critical exploration of the neglected dimension of the spatiality of knowledge formation in firms. The book concludes by discussing the corporate governance implications of learning based on competencies and communities, and a how national science and technology policies might respond to the idea of learning as a distributed, non-cognitive, practice-based phenomenon.