Heating and cooling (H&C) account for about half of Europe's total energy demand, with 75% still dependent on fossil fuels. Rapid and significant changes are therefore needed to meet the EU 2050 targets. Due to the local nature of H&C systems, action needs to be taken at the local level, involving a wide range of stakeholders. This has been recognized in recent years, and actions such as the development of best-practice strategies and open-source analysis tools have been initiated. Nevertheless, (efficient) H&C planning and project development are still not common in most European municipalities. The goals of Act!onHeat are to further disseminate and adopt the concept and methods for strategic H&C planning, to increase their quality, and to promote the development and implementation of the identified measures. To achieve these goals, Act!onHeat will conduct the following activities: (i) Identify the success factors of strong and efficient existing H&C plans and develop a workflow for strategic H&C planning and project development based on the existing open source tools Hotmaps and THERMOS, (ii) Support at least 120 communities in strategic H&C planning and the development of at least 30 pre-feasibility studies for relevant individual projects with a mix of tailored individual and group support activities, (iii) Training stakeholders who can actively contribute to decarbonization in the use of workflows, processes, and tools through a dedicated training program; and (iv) Achieving additional impact through a mix of pan-European roadshow events, acceleration dialogues, webinars, and other promotional activities.