Note: Specialization points are obtained at levels 7 and 14.

Mage
  Arcane Warrior: Learned from The Presence in Brecilian Ruins ("Nature of the 
  Beast" quest line). 
  Blood Mage: Learned from Desire Demon in Fade ("Arl of Redcliffe" quest line). 

  Shapeshifter: Learned from Morrigan (companion) or Varathorn (Dalish Camp). 
  Spirit Healer: Learned from Wynne (companion) or Wonders of Thedas (Denerim, 
  after Landsmeet starts). 

Rogue
  Assassin: Learned from Zevran (companion) or Alarith's Store (Denerim, after 
  Landsmeet starts). 
  Bard: Learned from Leliana (companion) or Alimar (Orzammar). 
  Duelist: Learned from Isabela (The Pearl in Denerim). 
  Ranger: Learned from Bodann's Wares (Party Camp). 

Warrior
  Berserker: Learned from Oghren (companion) or Gorim (Denerim Market). 
  Champion: Learned from Arl Eamon (at the end of the "Urn of Sacred Ashes" 
  quest line). 
  Reaver: Learned from Kolgrim (Wyrmling Lair). 
  Templar: Learned from Alistair (companion) or Bodahn's Wares (Party Camp).