This paper analyzes how international rules are established and stabilized, i.e. how an international institutional order develops. Rules emerge mainly through learning from negative experience and serve to reduce transaction costs. The paper looks at mechanisms that stabilize rule systems, at bargaining procedures for cooperation gains, dispute settlement, sanctions, side payments, self-enforcing contracts, waivers and regional integrations within a multilateral order. In addition it analyzes the prevention of negative spillovers, international courts and global public goods.