Involution occurs when something turns in upon itself. It may refer to:
- Involute, a construction in the differential geometry of curves
- Involution (agriculture), intensification of production through increased labour inputs
- Involution (mathematics), a function that is its own inverse
- Involution (medicine), the shrinking of an organ (such as the uterus after pregnancy)
- Involution (philosophy), a "turning in" on one's self
- Involution (esoterism), several notions of a counterpart to evolution
- Involution (Meher Baba), the inner path of the human soul to the self
- Involution (literature), a work that turns in on itself