Character ClassStrIntWisDexConCha
Cleric----9------
  Druid----12----15
  Monk13--151411--
Fighter9----------
  Cavalier129 129 
    Paladin1291312917
  Ranger131314--14--
Mage--9--------
Specialist Varies: see Wizard Specialist Reqts table
Thief------9----
Bard--13--12--17

Multi-class requirements...

Character ClassStrIntWisDexConCha
Cleric / Fighter9--9----*--
Cleric / Mage--99--14--
Cleric / Fighter / Mage999------
Cleric / Ranger131314--1415
Cleric / Thief----9912--
Druid / Fighter9--12------
Druid / Mage--912----15
Druid / Fighter / Mage9912----15
Druid / Illusionist--99------
Druid / Ranger131312--14--
Fighter / Illusionist99--16----
Fighter / Mage99--------
Fighter / Thief9----9--*--
Fighter / Mage / Thief99--9----
Illusionist / Thief--9--16----
Mage / Thief--9--9----

* Minimum 11 for Dwarves, 12 for Half-Orcs