Mitigation of climate change requires action at all the different levels, from the international to the national and the local levels. This contribution presents a case study of the city of Helsinki in Finland. An ex-post approach is used to follow the implementation of the EU directives to the national and further to the city level and to identify the relevant voluntary action taken in the city. We find that the coherence of national and city level policies is the highest in regulated areas, such as waste management and building regulation. Voluntary action is easily taken at local level in areas where co-benefits can be expected: e.g. energy conservation and biofuels for transportation. These voluntary actions can show the feasibility of certain measures which can later on be implemented at national or supranational level. We observe a clear contradiction between the EU and national renewable electricity targets and the nonaction at the city level: local conditions and private interests pose barriers to the implementation of a climate policy. We conclude that the coherence between policies at different levels develops over time and international requirements as well as local conditions can be drivers for it. Cities in particular play a role in mitigating climate change through removing barriers for the implementation of national and EU policies, and through moving forward with and promoting innovative voluntary measures, e.g. through international city networks.