In civil societies, urban movements are one of the tools in the process of spatial governance. In Poland, urban activism is beginning to develop together with a budding participation in public life. Therefore, there is a need to assess the scope and effects of the urban movements’ actions. The aim of the study was to determine and evaluate their impact on the spatial development in three Polish cities - Poznań, Gdańsk and Gdynia, especially in regard to the procedures in local urban planning and the process of participation. On the basis of the data collected during research and community interviews conducted in these cities, the following factors were analysed: the background and current profile of urban movements, the extent, regularity and effectiveness of their actions, the planning and spatial development initiatives undertaken, their cooperation with the local authorities and their contribution to the enhancement of participatory mechanisms.