The European Crystallographic Association (ECA) is an independent scientific organisation, representing both national crystallographic associations in Europe as well as individual members. ECA was founded in 1997. In May 2021 the association had 35 national and several hundred individual members. ECA is one of the regional affiliates of the International Union of Crystallography. The other independent regional affiliates are the American Crystallographic Association, the Asian Crystallographic Association and the Latin American Crystallographic Association. The association is registered under Dutch law in Zeist.