No members, no party. This is true of any party, but it goes doubly for an activist movement like the SP. Since the beginning of 2005 the SP has been, in terms of membership, the third biggest party in the Netherlands (compare the membership figures since 1992). And, amongst these 50,000 SP members, unprecedented numbers are actively involved in their party a good 38%, or well over a third of the membership. If you want to know more about SP members, a comprehensive survey is available.
In the SP, also, it is the members who take the decisions. The members directly elect their representatives to the Party Congress. In between congresses, the SP's highest decision-making body is the Party Council, on which sits, along with the executive committee, the directly-elected chair of each local branch. Congress resolutions, national candidates' lists, the election programme and all important decisions are first of all subjected to lengthy discussions in these branches.
Above all, it is the members who are responsible for the SP's many activities. No active socialists, no socialist party!