For centuries, the term "Guild" was used interchangeably with "class". Organisations centred around common skills and ideals, Guilds were led by a Guildmaster and his or her appointed secretaries. In the year 399 AF, however, Guilds became officially obsolete as the last of these organisations underwent conversion to Houses.
The following are the former Guilds of Achaea and their respective classes, listed in order of their conversion to Houses:
| GUILD | CLASS | HOUSE |
| Sentaari | Monk | The Sentaari |
| Sentinels | Sentinel | The Sentinels of Nature |
| Kharon | Monk | The Sect of the Black Lotus |
| Druids | Druid | The Ancient Circle of Druids |
| Paladins | Paladin | The Guardians of Light |
| Serpentlords | Serpent | The Cult of the Serpent Lords |
| Occultists | Occultist | The Occultists |
| Priests | Priest | The Empyreal Assembly |
| Shadowsnakes | Serpent | The Shadowsnakes |
| Magi | Magi | The Crystalline Circle |
| Warlocks | Magi | The Warlocks of the Rising Phoenix |
| Dawnstriders | Serpent | The Dawnstriders |
| Ashura | Monk | The Ashura |
| Runewardens | Runewardens | The Wardens of the Cerulean Spire |
| Mojushai | Monk | The Mojushai |
| Maldaathi | Infernal | The Maldaathi |
| Naga | Serpent | The Naga |
| Apostates | Apostate | The Blood Congregation |
| Sylvans | Sylvan | The Sylvanic Fellowship |
| Tanjinn | Monk | The Ebon Fist |
| Bards | Bard | Ty Beirdd |
| Shamans | Shaman | Spirit Walkers |
| Sorcerers | Magi | Merchants of the Crown |
| Arcanists | Magi | The Arcane Kindred |
| Jesters | Jester | Carnivalis Institute of Jestering |
| Infernals | Infernal | (destroyed in 299 AF) |