Guilds

From the publisher:

Add more detail and flavor to your d20 fantasy games with Guilds, a book that introduces arcane orders, fraternal brotherhoods, secret conspiracies, and other organizations. Member characters can receive training, material support, and social connections. Guilds introduces a new concept to the d20 system: chapters. A chapter is a social institution that pursues a specific goal. Characters can join chapters that match their aims, gaining access to training and other resources that improve their abilities and further customize their talents.