New social movements, focused around values and sociocultural identities, shape new communities outside the traditional field of party politics. On one hand, in their institutionalization, social movements enter the political sphere, and on the other, political parties strive to attract voters and supporters by application of tools typical for social movements. The subject of this paper is the border area between new social movements and parties, understood primarily as modes of collective action. The study aims at delineating the field of their mutual influence and at identifying its mechanisms, and explores the problems of ambivalence and instability affecting the dynamics of change within political systems.