All youth and most club ultimate games are self-officiated through the “Spirit of the Game," often abbreviated SOTG. Spirit of the game is an expectation that each player will be a good sport and play fair, including "following and enforcing the rules."

Ultimate has traditionally relied upon a spirit of sportsmanship which places the responsibility for fair play on the player. Highly competitive play is encouraged, but never at the expense of the bond of mutual respect between players, adherence to the agreed upon rules of the game, or the basic joy of play. Protection of these vital elements serves to eliminate adverse conduct from the ultimate field. Such actions as taunting of opposing players, dangerous aggression, intentional fouling, or other ‘win-at-all-costs’ behavior are contrary to the spirit of the game and must be avoided by all players.

Many tournaments give awards for the most spirited teams and/or players, often based on ratings provided by opposing teams. The largest youth ultimate tournament in the world, Spring Reign, uses spirit scores to award a spirit prize within each pool and to determine eligibility of teams the following year.[29] In many non-professional games, it is common for teams to meet after the game in a "spirit circle" to discuss the game, and in some cases grant individual spirit awards.

While "spirit of the game" is a general attitude, ultimate has an agreed upon procedure to deal with unclear or disputed situations.

In Europe and other countries, even top-level play does not have referees. Some world championship games have had no referees, and disputes were decided by the players themselves.

"Observers" are used in some high level tournaments outside the USA, as well as in some tournaments sanctioned by USA Ultimate. Disputes are initially handled by the players, but observers step in if no agreement is reached. In some settings, officials use a stopwatch to track the stall count and the defending players are not counting the stall.

Other forms of refereeing exist in ultimate. Professional ultimate in North America uses referees, in part to increase the pace of the game.