While, in practice, agile methods are increasingly used across large and distributed projects, the general applicability in large-scale development projects is still contested. Currently, there are only a few empirical studies of agile in the large, and especially accounts on how scaling is performed in practice are scarce. This paper aims at closing this gap by reporting from a case study of a large-scale agile effort in a highly prestigious IT-project in a Governmental organization in Norway. Theoretically, the paper draws from insights from studies of product innovation, and conceptualizes scaling in large-scale agile projects as a continuous process that involves establishing practices and artifacts for communicating and sharing across 'knowledge boundaries'. Empirically, the paper contributes by illustrating how scaling is made possible and performed through a wide-range of novel practices and artifacts that emerge over time. We illustrate how these practices, roles and artifacts establish ways of transferring, translating and transforming knowledge across different teams and between different stakeholders. Our analysis shows that these practices challenge a widespread dichotomy between agile methods as being 'flexible' on one hand, and traditional methods being 'rigid' on the other hand. Instead, the tailored practices in the case both added structure and flexibility at different stages in the process.