Municipalities are a central field of action for combating climate change and the transition to an ecologically sound, low-carbon energy system. In China and worldwide, most people live in cities and they are the level on which most climate and energy measures ultimately are implemented. What is particularly challenging to administrations and policymakers is that climate action is a cross-cutting task that affects all policy areas. Therefore, this kind of transformation requires an overarching plan. Sustainable Energy and Climate Action Plans (SECAP) represent such a plan and form a cornerstone of municipal climate action and energy transition in Germany and Europe.