Our contemporary societies are made of meta-organizations - organizations composed of other organizations. These range from international bodies like the International Whaling Commission, to national industry or business associations like the crowdfunding association Finance Participative France, to local associations such as fisheries co-management committees in Catalunya. Meta-organizations have become a defining feature of how actors coordinate, govern and make collective decisions. But what exactly makes them distinct, and why do they matter - both in theory and in practice?This books delves into the importance, characteristics and diversity of meta-organizations. It explores four interrelated perspectives: meta-organizations as a widespread, heterogeneous empirical phenomenon in contemporary society, as a conceptual framework that raises specific methodological challenges, as part of a broader theory of decision-based social orders, and ultimately as arenas where hegemonic and counter-hegemonic dynamics may unfold.By bridging theory and practice, this work offers new insights into how meta-organizations operate, how they can be studied and understood, the problems they raise and what they can achieve under certain conditions - making it essential reading for practitioners, students, scholars, and policymakers alike.