The panto has a number of conventions, some of which have changed or weakened a little over the years, and by no means are all obligatory.
- The leading male juvenile character (the principal boy) is traditionally played by a young woman in male garments (such as breeches). Her romantic partner is usually the principal girl, a female ingénue.
- An older woman (the pantomime dame – often the hero's mother) is usually played by a man in drag.
- Risqué double entendre, often wringing innuendo out of perfectly innocent phrases. This is, in theory, over the heads of the children in the audience and is for the entertainment of the adults.
- Audience participation, including calls of "He's behind you!" (or "Look behind you!"), and "Oh, yes it is!" and "Oh, no it isn't!" The audience is always encouraged to hiss the villain and "awwwww" the poor victims, such as the rejected dame, who is usually enamoured with one of the male characters.
- Music may be original but is more likely to combine well-known tunes with re-written lyrics. At least one "audience participation" song is traditional: one half of the audience may be challenged to sing "their" chorus louder than the other half. Children in the audience may even be invited on stage to sing along with members of the cast.
- The animal, played by an actor in "animal skin" or animal costume. It is often a pantomime horse or cow (though could even be a camel if appropriate to the setting), played by two actors in a single costume, one as the head and front legs, the other as the body and back legs.
- The good fairy enters from stage right (from the audience's point of view this is on the left) and the villain enters from stage left (right from the point of view of the audience). This convention goes back to the medieval mystery plays, where the right side of the stage symbolised Heaven and the left side symbolised Hell.
- A slapstick comedy routine may be performed, often a decorating or baking scene, with humour based on throwing messy substances.
- The Chorus, who can be considered extras on-stage, and often appear in multiple scenes (but as different characters) perform a variety of songs and dances throughout the show. Because of their multiple roles, they may have as much stage-time as the lead characters themselves.
- At some point during the performance, characters including the Dame and the comic will sit on a bench and sing a cheerful song to forget their fears. The thing they fear, often a ghost, appears behind them, but at first the characters ignore the audience's warnings of danger. The characters soon circle the bench, followed by the ghost, as the audience cries "It's behind you!" One by one, the characters see the ghost and run off, until at last the Dame and the ghost come face to face, whereupon the ghost, frightened by the visage of the Dame, runs away.