This review of climate change legislation in 33 countries shows that developing countries are leading action on climate change. Overall, there has been significant progress in the climate and/or energy-related legislation of almost all major economies, but a great amount of the 2012 effort took place in emerging countries. In particular, among major economies Mexico and China are leading the action against climate change thanks to their recent steps to cut carbon emissions and raise energy efficiency. The study aims to support legislators advancing climate-related legislation by providing detailed information on existing legislation to help identify gaps, best practice and encourage peer-to-peer learning. It also hopes to provide positive momentum to the international climate change negotiations. According to the review, legislative action at the national level is a fundamental prerequisite to achieving global climate change mitigation goals.