Chaos theory is a scientific theory describing erratic behavior in certain nonlinear dynamical systems.

Chaos Theory may also refer to:

• The Chaos Theory, a 2002 album by Jumpsteady
• Chaos Theory, a 2005 video game
• Chaos Theory – Splinter Cell 3 Soundtrack
• Chaos Theory (film), a 2008 comedy-drama film
• "Chaos Theory" (ER)
• "Chaos Theory" (CSI)
• "Chaos Theory" (The Unit)
• Chaos Theory (demo)
• The third episode of the video game Life Is Strange
• Chaos Theory (Agents of S.H.I.E.L.D.), an episode of the American television series Agents of S.H.I.E.L.D.

• Letter to the Ephesians
• Letter to the Galatians
• Letter to the Grand Duchess Christina
• Letter To the Hebrews
• Letter to the Philippians
• Let That Be Your Last Battlefield
• Let the Blood Run Free
• Let the Boots Do the Talking
• Let the Eagle Soar
• Let the eagle soar
• Let the love begin
• Let the Love Begin (film)
• Let Them Eat Cake (TV series)
• Let the Moreno Play Movement
• Let the Music Do the Talking
• Let the Music Play (song)
• Let there be light
• Let There Be Love (Oasis song)
• Let There Be Rock
• Let There be Rock
• Let the Sunshine In (album)
• Let the Thunder of Victory Rumble! (anthem)
• Lettice Boyle
• Lettice Knollys
• Lettie Viljoen