What are the practices of policy making? In this paper, we seek to identify and understand them by attending to one of the principal artefacts--the document--through which they are organised. We review the different ways in which researchers have understood documents and their function in public policy, endorsing a focus on content but noting that the processes by which documents are produced and used have been left largely unexamined. We specify our understanding of the document as an artefact, exploring aspects of its materiality in both paper and electronic forms. The key characteristic of the policy document, we suggest, is the way it is produced and used collectively, in groups.