Twinning (making a twin of) may refer to:
- In biology and agriculture, producing two offspring (i.e., twins) at a time, or having a tendency to do so;
- Twin towns and sister cities, towns and cities involved in town twinning
- Twinning institutional building tool
- eTwinning, a collaboration in which two schools in different locations are paired and communicate using the internet
- Afri Twin, an exchange partnership between schools in the United Kingdom and South Africa
- Twinning (roads), construction of one road next to another
- In crystallography, crystal twinning refers to intergrown crystal forms that display a twin boundary
- In film, special effects that multiply the presence of the same actor or actress on screen
- In animation, twinning refers to when two parts on opposite sides of a character's body move the same way
- A type of transnational education in which a student does part of their degree course in a local private college and part of it in an overseas institution tied to the college
- Twinning (TV series), a 2015 reality show on VH1
- A practice by which Jewish boys and girls approaching their Bar or Bat Mitzvah in the United States were symbolically paired with a child of the same age in the Soviet Union who was disallowed from practicing religion.