Once upon a time – indeed not that long ago – it was quite easy to say what was public and what was private. Public was associated with the state and its citizenry as a whole, the general public. These were counterposed to the private, which referred to individuals, on their own, or organized in some particular or intimate way, in firms or families. As Best and Gheciu argue (Chapter 2, this volume), we are emerging from a period in which the private was greatly expanded at the expense of the public, to one in which the public is re-emerging, but in different forms than previously. These new forms involve public practices. We can no longer simply assume that activities associated with the state or its citizenry as a whole are public. Instead we need to pay close attention to the “knowledge-constituted, meaningful patterns of socially recognized activity that structure experience and that enable agents to reproduce or transform their world,” to use Best and Gheciu's definition of practices. As they argue, public practices are ones that involve matters of common concern. Already in these definitions the greater difficulty of identifying what is public is evident. The definitions involve a complex interplay between their social aspects (knowledge, social recognition, common concerns), which are closer to the collective character of older conceptions of the public, and the role of agents, which could be individuals or collectivities, but operating in a more particular manner that is closer to the older conceptions of the private. As Best and Gheciu note, this public is a more ad hoc construction involving certain actors or processes at certain moments.