16 Apr 2009 12 Jul 2009
To get this achievement, you will need to join any of the many guilds. (Cooking, Fishing, etc.) Once this is done, talk to the bard that changes your title for 200 gil. If you scroll down below the option that says "Let bard choose my title" you will find "unlock achievement". Click it. When you click it, there will be a screen that either has a name of an achievement, or it will say "more". If it doesn't have a name, but it has "more" click it. You will then see the name of this achievement, Guild Member. When you click it, The achievement unlocks, and the game tells you there are no more achievements to unlock. 5 GS.
EDIT: Guild Membership - 5G