Four square is a ball game.

Four square may also refer to:

• Foursquare City Guide, a local search and discovery app
• 4 Square (game show), a British game show
• 4 Square (TV series), a Canadian children's show
• 4 Square (pinball), a pinball machine
• Handball (school), an Australian ball game

• Foursquare (company), a technology company and the developer of Foursquare City Guide
• Four Square supermarkets
• Four Square Laundry, a front company for a British Army intelligence unit in 1970s Belfast
• Foursquare Church

• Four Square (Smithfield, Virginia), U.S., a historic home and farm
• Four square writing method
• American Foursquare, an architectural style
• Four Square (cigarette)

• Russian four square
• Four-square cipher
• Lagrange's four-square theorem, any natural number equals the sum of four integers squared
• Jacobi's four-square theorem giving the number of distinct ways an integer can be represented as the sum of four squares
• Euler's four-square identity or theorem, the product of two numbers, each of which is a sum of four squares, is itself a sum of four squares.
• Ariel Square Four, a motorcycle