The United Nations General Assembly, by its resolution 65/159, of 20 December 2010, invited the secretariat of the United Nations Framework Convention on Climate Change1 to report to it at its sixty-sixth session on the work of the Conference of the Parties (COP). This report is submitted in response to that invitation. The conference was held in Cancun, Mexico from 29th November to 10th December 2010, and comprised the following sessions: 1. The sixteenth session of the COP. 2. The sixth session of the COP serving as the meeting of the parties to the Kyoto Protocol. 3. The thirty-third session of the Subsidiary Body for Implementation. 4. The thirty-third session of the Subsidiary Body for Scientific and technological advice. 5. The fifteenth session of the Ad Hoc Working Group on further commitments for Annex I parties under the Kyoto Protocol. 6. The thirteenth session of the Ad Hoc Working Group on Long-Term Cooperative Action under the convention.