The article considers the peculiarities of the reforms of the territorial organization of power at the municipal level in Northern European countries. The reforms are aimed at developing the local self-government system, as well as increasing the efficiency and improving the coordination of services provided by local communities. In this regard, the article studies the content of the two main directions of local territorial reforms in European countries, which began in the twentieth century and continue today. These directions are based on encouraging local communities to collaborate through a network of organizations for inter-communal cooperation and/or community consolidation through mergers to properly fulfil municipal and administrative functions.The approaches used in Denmark, Norway and Finland to ensure greater efficiency of the local government system and to create capable local communities, which can more effectively perform the tasks of local self-government, have been analysed. The peculiarities of municipal reforming in Norway, characterized by consistency and the clear definition of the steps of its implementation, have been revealed; the results of reducing the number of municipalities have been shown. The specifics and stages of municipal transformations in Finland, during which measures were taken to encourage municipalities to merge freely, have been analysed; the reasons that negatively affected the implementation of local self-government reform at the local level have been highlighted. It has been concluded that there is a common trend for these countries to create larger municipalities through mergers, which is more effective applying coercive measures and state incentives to amalgamate local communities.