EFF may refer to:

• The Effective Federal funds rate
• Electronic Frontier Foundation, a U.S. non-profit advocacy group
• Elf Fantasy Fair
• Economic Freedom Fund, a U.S. political organization
• Equipped for the Future, a U.S. non-profit adult literacy project
• Election Fighting Fund, a UK fundraising organisation in the 1910s
• Ethiopian Football Federation, the governing body of football in Ethiopia
• Evergreen Freedom Foundation, a U.S think-tank
• European Fisheries Fund, a fund allocated by the European Union
• DC Environmental Film Festival, a festival held annually in Washington, DC

Eff may refer to:

• The English spelling of the letter f
• The pronunciation equivalent of an F indicating a failing grade in the US Education Grading System
• A euphemism for the word fuck

EFF may refer to:

• The Effective Federal funds rate
• Electronic Frontier Foundation, a U.S. non-profit advocacy group
• Economic Freedom Fund, a U.S. political organization
• Equipped for the Future, a U.S. non-profit adult literacy project
• Election Fighting Fund, a UK fundraising organisation in the 1910s
• Ethiopian Football Federation, the governing body of football in Ethiopia
• Evergreen Freedom Foundation, a U.S think-tank
• European Fisheries Fund, a fund allocated by the European Union

Eff may refer to:

• The English spelling of the letter f
• The pronunciation equivalent of an F indicating a failing grade US Education Grading System
• A euphemism for the word fuck