Cities and local authorities are key players in addressing climate change. Since 2008, the European Commission (EC) endorses and supports their efforts through the Covenant of Mayors for Climate and Energy (CoM) and notably through the provision of capacity building, technical assistance, sharing of best practices and peer learning opportunities. The initiative helps consolidate practices to monitor and report on energy consumption and greenhouse gas (GHG) emissions as well as on risks and vulnerabilities at the local level, enabling decision makers to identify priority sectors, set emission reduction targets and adaptation goals and plan relevant measures. This report provides a scientific assessment of the CoM pillars of climate change mitigation and adaptation, focusing on Europe. It describes the Covenant community, the plans submitted by signatories, examines actions and measures and gives an overview on the progress made. The key findings on mitigation show that the overall commitment to reducing GHG emissions by 1 631 signatories in EU-27 is 55.2 % by 2030 compared to baseline emissions. Looking only at 676 action plans accompanied by at least one monitoring report, a 48 % reduction by 2030 is forecasted, while the targeted mean reduction is 56 %. This insight suggests that greater effort is necessary for signatories to advance in the implementation of their action plans and achieve the emission reduction targets they have set. On adaptation, the report shows that several vulnerable population groups including the elderly, persons with chronic diseases, low-income households, and persons living in sub-standard housing, are exposed to climate hazards. Signatories report high-risk hazards (such as extreme heat, droughts & water scarcity, heavy precipitation and floods & sea level rise) that affect 65.3 million people.