Cities play a crucial role in reducing CO2 emissions. In order to support the efforts of local authorities, the European Commission launched the Covenant of Mayors (CoM). CoM signatories commit to reduce CO2 by at least 20%in 2020, to prepare a Baseline Emission Inventory (BEI) and to submit a Sustainable Energy Action Plan (SEAP). The paper aims to assess the distribution of intended emission reductions by cities among sectors and to evaluate the relevance of the policies and actions adopted by cities. The analysis is based on data provided by a subset of cities participating in the CoM: the sample is composed of 124 cities implementing more than 5500 actions. Cities in the sample account for a total of 370 megatons of CO2 emissions, the total emission reduction planned by cities corresponds to 25% of baseline emissions. Emission reductions are concentrated in the Building and Transport sectors. The sectoral analysis points that actions in sectors under the direct control of cities' administrations are planned to deliver higher reductions. In both the Building and Transport sectors, cities plan to reduce the major amount of CO2 emissions through the implementation of management and organization, infrastructure construction, and awareness-raising infrastructure policy levers.