The International Association of Classification Societies (IACS) is a technically based organization consisting of twelve marine classification societies headquartered in London.

Marine classification is a system for promoting the safety of life, property and the environment primarily through the establishment and verification of compliance with technical and engineering standards for the design, construction and life-cycle maintenance of ships, offshore units and other marine-related facilities. These standards are contained in rules established by each Society. IACS provides a forum within which the member societies can discuss, research and adopt technical criteria that enhance maritime safety.