Classification societies are organisations which develop and apply technical standards to the design, construction and assessment of ships (and other marine facilities) and which carry out survey work on ships. Flag states can authorise classification societies for the inspection and statutory certification of their ships. There are more than 50 organisations worldwide which define their activities as providing marine classification, but only 12 classification societies (see below) are presently recognised by the European Union (Official Journal C 135/04 of 19 June 2007).

Only Member States can request EU recognition of a classification society and the enlargement of the EU may lead to additions to the EU recognised list. EU Member States can only authorise a classification society recognised by the European Union.

The main Union legislation that deals with classification societies is Regulation (EC) No 391/2009 and Directive 2009/15/EC (as amended after the Erika disaster). In accordance with this, the Commission assesses each of the 12 EU recognised classification societies once every two years. EMSA has been entrusted by the Commission with the task of carrying out the necessary inspections on its behalf. EMSA therefore organises a number of inspections per year, which cover both head offices and selected regional, field and site offices, and also include visits to ships for the purpose of checking the performance of the classification society in question. EMSA also carries out the necessary inspections whenever the Commission needs to assess classification societies for which EU recognition is being requested by one or more Member States.