List of treaties by number of parties

This article contains a list of treaties by number of parties to the treaty. A "party" to a treaty is a state or other entity that ratifies, accedes to, approves, or succeeds to the treaty.

In general, multilateral treaties are open to ratification by any state. Some treaties may also be ratified by supranational bodies, such as the European Union, and by other international organizations.

In practice, the depositary of a treaty will usually only recognise ratifications of the treaty that are performed by a state that is recognised as a state at international law. A state can be formally recognised as such by becoming a member of the United Nations; there are currently 193 member states of the United Nations. The only non-UN states that undoubtedly meet the standard of statehood are the Cook Islands and Niue, who have had their "full treaty-making capacity" recognised by the United Nations Secretariat. The Holy See—while not a state per se but an entity closely tied to the state of Vatican City—is also widely recognised as being able to legitimately ratify treaties and has been granted non-member observer state status by the UN General Assembly. Following the UNGA passing a resolution granting non-member observer state status to the State of Palestine, the UNSG has begun to recognize its right to ratify treaties. Ratifications performed by other states with more limited recognition—such as the Republic of China (Taiwan); Kosovo; Northern Cyprus; Somaliland; the Sahrawi Arab Democratic Republic (Western Sahara); South Ossetia; Abkhazia; Transnistria; and Nagorno-Karabakh—have usually not been recognised by treaty depositaries as states that can ratify treaties, although there are some exceptions to this general rule.

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