IIA or Iia may refer to:
- Independence of irrelevant alternatives
- Indian Institute of Architects
- Indian Institute of Astrophysics
- Indianapolis International Airport
- Institute of Internal Auditors
- Information Industry Association
- International Investment Agreement
- Islamabad International Airport
- IIa or II-a, a subtype of Type II supernova
- A rating in the Hong Kong motion picture rating system
- Iia, Estonia, village in Estonia
See also
edit- 2A (disambiguation), including a list of topics named II-A, etc.