In 2373, the United Federation of Planets consisted of at least 150 member planets, spread over 8,000 light years. (Star Trek: First Contact)
We may assume, that the admission policy of the Federation regards governments and/or planets, and not whole species. In practice, a planet has to be unified under one joint government until it can apply for Federation-membership. However, there are exclusions like the Kes, thus rendering a single planetary government preferable but not obligatory.
Founding members
The Founding Ceremony
The United Federation of Planets was founded in 2161 by the following members:
- Andoria
- Homeworld of the Andorians and the Andorian Empire. (ENT: "Zero Hour", "These Are the Voyages...")
- Earth
- Homeworld of the Humans and United Earth. (ENT: "Zero Hour", "These Are the Voyages...")
- Tellar Prime
- Homeworld of the Tellarites (ENT: "Zero Hour", "These Are the Voyages...")
- Vulcan
- Homeworld of the Vulcans and the Vulcan High Command. (TNG: "Gambit, Part II"; ENT: "Zero Hour", "These Are the Voyages...")
According to "It's Federation Day!", a newspaper article created as background material for Star Trek Generations, the independent Alpha Centauri colony was another Federation founding member.
Council members
The following are members of the Federation who are known to be on the Federation Council.
- Arcadian homeworld
- Homeworld of the Arcadians (Star Trek IV: The Voyage Home)
- Ariolo homeworld
- Homeworld of the Ariolo (Star Trek IV: The Voyage Home)
- Bzzit Khaht homeworld
- Homeworld of the Bzzit Khaht (Star Trek IV: The Voyage Home)
- Caitian homeworld
- Homeworld of the Caitians (Star Trek IV: The Voyage Home)
- Delta IV
- Homeworld of the Deltans (Star Trek IV: The Voyage Home)
Jaresh-Inyo, the Grazerite Federation President in 2372
- Grazerite homeworld
- Homeworld of the Grazerites (DS9: "Homefront")
- Kasheeta homeworld
- Homeworld of the Kasheeta (Star Trek IV: The Voyage Home)
- Xelatian homeworld
- Homeworld of the Xelatians (Star Trek IV: The Voyage Home)
- Zaranite homeworld
- Homeworld of the Zaranites (Star Trek: The Motion Picture, Star Trek IV: The Voyage Home, Star Trek VI: The Undiscovered Country)
Other known members
The following are members of the Federation who may or may not have Council privileges.
- Aaamazzarite homeworld
- Homeworld of the Aaamazzarites. (Star Trek: The Motion Picture)
- Algolian Homeworld
- Homeworld of the Algolians. (TNG: "Qpid")
Based on them having a seat on the Federation Archaeology Council.
- Arbazan Homeworld
- Homeworld of the Arbazan. (DS9: "The Forsaken")
Based on an Arbazan holding the position of Ambassador.
- Ardana
- Homeworld of the Ardanans. (TOS: "The Cloud Minders")
- Benzar
- Homeworld of the Benzites. (TNG: "Coming of Age")
- Betazed
- Homeworld of the Betazoids. (TNG: "Haven")
- Bolarus IX
- Homeworld of the Bolians. (DS9: "The Forsaken")
There is some ambiguity about the Bolian status as federation members. See the article on the species for more information
Ambassadors Sarek and Gav discuss Coridan's admission into the Federation in 2268
- Coridan
- Homeworld of the Coridans. (TNG: "Sarek")
- Hekaras II
- Homeworld of the Hekarans. (TNG: "Force of Nature")
- Peliar Zel II
- Homeworld of the Peliar Zel natives. (TNG: "The Host")
- Rigel IV
- Homeworld of the Rigellians. (Star Trek: The Motion Picture)
- Risa
- Homeworld of the Risians. (TNG: "Captain's Holiday")
- Zakdorn Homeworld
- Homeworld of the Zakdorn. (TNG: "Peak Performance")
Protectorates
- Evora Homeworld
- Homeworld of the Evora. (Star Trek: Insurrection)
Haven was said to have a treaty with the Federation which required Starfleet to protect it, and thus may have been an official protectorate.
Colonies
See Federation colonies.
The exact status of Federation colonies has never been clearly established. While due to the large amount of colonies it seems unlikely that they have full member status, it would be plausible to assume that they enjoy a status not unlike to that of Federation protectorates.
Proposed members
Captain Benjamin Sisko stopping Bajor from joining the Federation
These following were in the process of gaining Federation member status as of the year indicated.
- Angosia III (2366)
- Homeworld of the Angosians. (TNG: "The Hunted")
- Antede III (2365)
- Homeworld of the Antedeans. (TNG: "Manhunt")
- Antica (2364)
- Homeworld of the Anticans. (TNG: "Lonely Among Us")
- Bajor (2377)
- Homeworld of the Bajorans. (DS9: "Emissary")
- Cairn Homeworld (2370)
- Homeworld of the Cairn. (TNG: "Dark Page")
- Catulla (2269)
- Homeworld of the Catullans. (TOS: "The Way to Eden")
- Gideon (2268)
- Homeworld of the Gideon natives and the Gideon Council. (TOS: "The Mark of Gideon")
- Kesprytt III (2370)
- Homeworld of the Kesprytt and the Kes and Prytt governments. (TNG: "Attached")
- Selay (2364)
- Homeworld of the Selay. (TNG: "Lonely Among Us")
{{bginfo|Bilana III was a member according to the Star Trek Encyclopedia