Reaching the 1.5°C target of the Paris Agreement not only requires ambitious goals from national governments, but also the active participation of local municipalities. It is in cities where climate actions need to be implemented to reduce greenhouse gas emissions and reach the international and national climate goals. While the importance of cities and their participation in networks has been well researched, studies have systematically neglected the committed individual agents in small and medium-sized cities and overlooked the importance of national networks. To address these research gaps, this thesis firstly investigates the key factors influencing climate policy implementation in small and medium-sized Danish municipalities. Secondly, it looks at how local climate managers use their municipality’s membership in national networks to increase this action implementation. To gather empirical data, twelve semi-structured interviews with seven municipal representatives and five representatives of two national city networks, and four informal discussions were held. Documents were also collected and analyzed. Through comparative content analysis, it was found that the main functions derived from network participation are direct exchanges between the climate managers, mobilization of others in the municipality, accounting of greenhouse gas emissions, and project support. These functions helped overcome key limitations the actors faced within the municipality related to a lack of legal competences, administrative resources and internal support for climate work and financial resources. This has implications for city networks which have been focusing on larger cities and not including smaller cities who have less capacity and would benefit most from the functions provided by them. Key recommendations are that small and medium-sized municipalities should join municipal networks since they have a high potential to gain from them to overcome inherent barriers associated with lower capacity. Moreover, municipal networks should tune their offerings to fit the diverse needs of their members and to not only focus on large and already ambitious cities but also smaller ones and newcomers. Lastly, future research should be done on national adaptation networks to compare with the findings from this thesis. To conclude, this thesis shows how small and medium-sized municipalities can take on ambitious climate plans and actions through collaborations and truly using the power in working together.