The role of guilds in the premodern economy has been the subject of much, and at times heated debate in recent times. However, about one thing the contestants are all agreed: guilds made a difference. In this paper we will look not so much at the benefits and disadvantages of guilds for economic development, but at their social make-up. Special attention will be paid to their (presumed) exclusiveness: how difficult was it to join a guild, and did guilds actually manage to protect monopoly rents through exclusive membership?