In 2373, the United Federation of Planets consisted of at least 150 member planets, spread over 8,000 light years. (Star Trek: First Contact)
Founding members
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...")
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)
- Grazerite homeworld
- Homeworld of the Grazerites. (DS9: "Homefront")
- Kasheeta homeworld
- Homeworld of the Kasheeta. (Star Trek IV: The Voyage Home)
- Unnamed Federation planet
- Home to the unnamed alien council members. (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
- Arbazan Homeworld
- Homeworld of the Arbazan. (DS9: "The Forsaken")
- 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. (TNG: "Qpid"; DS9: "The Forsaken")
- Coridan
- Homeworld of the Coridans. (TNG: "Sarek")
- Efrosian homeworld
- Homeworld of the Efrosians. (Star Trek VI: The Undiscovered Country)
- Hallia Homeworld of the Haliians. (TNG
- "Aquiel")
- Ktaris Homeworld of the Ktarians. (VOY
- "Child's Play")
- Hekaras II Homeworld of the Hekarans. (TNG
- "Force of Nature")
- Magna Roma aka Planet 892-IV {http://memory-beta.wikia.com/wiki/Magna_Roma Memory Beta}
- 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")
- Trillius Prime
- Homeworld of the Trills. (DS9: "Emissary"); (ENT: "Broken Bow")
- Unnamed Federation planet
- Home to the unnamed alien ambassadors. (TOS: "Journey to Babel")
- Unnamed Federation planet
- Home to the unnamed copper-skinned aliens. (TOS: "Journey to Babel")
- Unnamed Federation planet
- Home to the unnamed delegates. (TOS: "Journey to Babel")
- Unnamed Federation planet
- Home to the unnamed female delegates. (TOS: "Journey to Babel")
- Unnamed Federation planet
- Home to the unnamed purple-skinned aliens. (TOS: "Journey to Babel")
- Unnamed Federation planet
- Home to the unnamed robed delegates. (TOS: "Journey to Babel")
- Zakdorn Homeworld
- Homeworld of the Zakdorn. (TNG: "Peak Performance")
Protectorates
- Evora Homeworld
- Homeworld of the Evora. (Star Trek: Insurrection)
Colonies
See Federation colonies.
Proposed members
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 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")
Background information
In TOS: "Journey to Babel", set in 2268, the ambassadors of Federation planets attended the Babel Conference, at that time there were 32 ambassadors, suggesting there were at least 32 planets in the Federation at that time.
According to a dossier on the home page of Star Trek, in the alternate reality, the Federation had 120 member planets and 700 colonies in the 2250s. [3]
According to Star Trek: Star Charts (United Federation of Planets IV), in 2378, there were 183 members and 7,128 affiliates. The area of the Federation was 8,000 cubic light years. At the last census, in 2370, there were 985 billion individuals living in the Federation.
Aleek-Om was identified as a "Federation historian" in the Star Trek Concordance, possibly based on the script, suggesting Aurelia might be a member. Bilana III was also identified as a member in the Star Trek Encyclopedia and Star Trek: Star Charts.