Institutions and organizations are at the heart of every type of environmental policy. ‘Institutions’ are common arrangements established (instituere – establish) by actors in society to regulate their relations, ranging from the United Nations prohibition of the use of force, through to the institution of marriage. In political science, the particular political importance of institutions has led over the past decade to a renaissance of the study of institutions with theories of ‘New Institutionalism’. In international politics, the key institutions are termed ‘international regimes’, the term referring to a body of common principles, norms, rules and decision-making procedures among international actors (usually states). In most instances, institutions in international relations are connected intimately to ‘organizations’, the latter term meaning administrative units with their own budget, personnel and letterhead.This definition of organizations refers to establishments as administrative units with the above attributes, and not to the status under international law that any ‘organization’ within the UN system may have (Section E 2).The climate regime, for instance, is an institution that regulates the behaviour of its parties in the interests of climate protection and imposes certain obligations upon them; the Climate Secretariat in Bonn is a small international organization.