The Philadelphia Experiment an urban legend about a supposed U.S. Naval experiment on invisibility carried out in 1943.

Philadelphia Experiment can also refer to:

• The Philadelphia Experiment (film), a 1984 science fiction film
• Philadelphia Experiment II, the 1993 sequel
• The Philadelphia Experiment, a 2012 made for TV film, starring Malcolm McDowell and Nicholas Lea
• The Philadelphia Experiment (album), a 2001 collaborative jazz album featuring Uri Caine, Questlove, and Christian McBride
• The Philadelphia Experiment (Frost album), a live album by English progressive rock band Frost

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