Two ideas are almost universally accepted as reality in political sociology. One is that numbers are declining in nearly all membership associations. The usual interpretation of this phenomenon is that it occurs because of individualization. The other is that the character of collective action has changed. This idea, which stems from Touraine, Melucci and Castells, states that a new historical category of social action has emerged, one that resembles action in primary groups rather than in organizations and in some way is a victory over the iron law of oligarchy. This article questions both ideas. The author intends to show that another historical process is in play here, namely, a process of ‘inert rationalization’ in social movements, political parties and associations, which is taking place in Europe with different starting points and at different tempos. The result of this process can be summed up as ‘more organization with fewer people’. Domination, inherent in oligarchic organizations, is being transformed by the creation of a new organizational boundary between elite (or profession) and members. The point is that it is membership itself as a form for affiliation that is disappearing, not just members. The article argues that this is mainly because resource mobilization patterns have historically changed from the mobilization of resources drawn from members to the mobilization of resources drawn from other organizations. Finally, the article analyses the importance of the unstructured power fields (or open spaces) created by rationalization processes for social innovation and new social movements.