- ACTO stands for Advocacy Centre for Tenants Ontario (Toronto, Ontario, Canada)
- ACTO stands for Action Officer
- ACTO stands for Association for Counselling and Therapy Online (website; est. 2006)
- ACTO stands for Alliance of Concerned Transport Organizations (Philippines)
- ACTO stands for Amazonian Cooperation Treaty Organization
- ACTO stands for Army Communicative Technology Office
- ACTO stands for Association of Charter Train Operators (UK)
ACTO