Book excerpt: The book explores the various means of making non-conventional/non-treaty law and the cross-cutting issues that they raise. Law-making by technical/informal expert bodies, Conferences of Parties, international organizations, the UN Security Council, regional organizations and arrangements and non-state actors is examined in turn. This forms the basis for the analysis of the complementarity of international treaty law, customary international law and non-traditional law-making, potential subject matters of non-treaty law-making, domestic consequences of non-treaty law-making, proliferation of actors, commissions and treaty bodies of the UN system, and International courts and tribunals.