The world seems to lack consensus on this issue. Here's my unscientific survey of the books we have XMLized (XMLised?) so far: Magicians Guild 01fftd tmc (3x) Magicians' Guild 01fftd (illustration caption - we may have altered this) magician's guild 01fftd 02fotw (2x) 09tcof 14tcok tmc (2x) Magician's Guild 03tcok (3x including one illustration caption - we may have altered this) 05sots 12tmod No real consensus, but there's definitely a preference for the possessive. The problem is that I doubt that any form of "magician's" (singular possessive) is correct. I vote for "Magicians' Guild", "Thieves' Guild" and so on. -- Jon