Parallel to the implementation of the Kyoto Protocol, a growing number of companies and private individuals are making a voluntary commitment to offset their greenhouse gas emissions. The voluntary offset market is rapidly growing, with over 10 million tons of CO2 resulting from emissions reduction projects already being traded. Voluntary offsetting finances projects that are not subject to the “Kyoto” methodological framework, are often smaller, varied and sometimes innovative. This diversity is a source of richness, but the vagueness of the methodological rules and low product traceability can allow for poor quality projects and does not provide secured information for the buyer. This results in a troubling lack of price uniformity. The various quality labels and good-conduct approaches should permit progress towards improved product standardization and the emergence of a genuine market. Voluntary offset projects are most often developed in forestry and renewable energies sectors. Voluntary compensation projects involving industrial gases (N2O and fluorinated gases) are far less common than those under the Kyoto Protocol.