The Socialist party of the Netherlands (SP) is one of Europe's most successful left-wing parties. At a point in history where other left-wing forces are struggling just to maintain their membership, the Dutch left grows stronger every year. The result is not only one election victory after the other but the SP has also become a mass party with tens of thousands of members which allows for impressive street manifestations as a part of their campaign work. The party has especially strong support among workers. The SP was the driving force in the "NO-campaign" that led to the rejection of the centralistic and market liberal proposal for an EU constitution by Dutch voters. Looking from the US, we can ask how a modern socialist mass party can be built and grow so quickly in a country not known for its left wing traditions. The NYC Local of the Socialist Party USA is happy to invite