Abstract This chapter critically discusses the origin, structure and prospects of the Kyoto Protocol with a particular focus on the flexible mechanisms at the core of the regulatory framework set up by the Protocol. In doing so, it seeks to answer the following questions: (i) What has the impact of the Protocol been in mitigating climate change? (ii) What reasons can account for such outcome? (iii) What can we learn from past experience with the Kyoto Protocol and what could such experience mean for the future of the Protocol and more broadly the climate change regime? The goal is to identify some of the main legal challenges faced by the Protocol and to point to issues for further legal research.