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, an EU collaboration project 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