This report deals with international environmental instruments aimed at a cost-effective reduction of greenhouse gas emissions. More precisely the instruments mentioned in the Kyoto Protocol, namely Joint Implementation (JI), the Clean DevelopmentMechanism (CDM) and Tradable Permits (TP). The report describes the background for the international co-operation on reducing the greenhouse gases and the background for the instruments. How the instruments work in theory and what the practical problemsmay be. What agents' incentives are when they engage in JI or CDM, and how the initiation of the instruments can be organised. The institutional frameworks for JI, CDM and TP are discussed. The report describes how the Kyoto instruments and the Kyotocommitments interact with other instruments and describe distributive effects between countries. It is analysed how the use of CDM may influence the developing countries incentives to participate in the coalition of committed countries. In the concludingchapter some recommendations on the use of JI, TP and CDM are given. The recommendations are a kind of dialog with especially the Norwegian and Swedish reports on tradable permits. Some of the issues described in this main report are analysed in separateworking papers. The working papers are collected in an appendix to the main report.