Federation Day was a day of celebration commemorating the founding of the United Federation of Planets.
Deanna Troi suggested playing this game to the rest of the senior staff members of the USS Enterprise-D in 2368, however, Worf found it difficult to ascertain exactly what he had in his hand with so many wild cards. (TNG: "The Outcast")
Non-canon sources have established several dates for the event:
- October 11 - "It's Federation Day!", a newspaper clipping created for Star Trek Generations but not seen on screen.
- August 12 - in the last chapter of the novel Last Full Measure and also in the novel To Brave the Storm
- May 8 - background in the Star Trek: Star Charts
- June 30 - Listed on a memorial plaque at Starfleet Academy in Star Trek Online.