This article examines the various references to Athenian Dionysian festivals that are scattered throughout Aristophanes' Frogs, in order to establish the function they perform and how they contribute to shaping the personality of Dionysus, the play's protagonist. The Lenaia are alluded to as the festival on which the comedy premiered, and the Anthesteria because they temporarily opened the world of the dead, which is appropriate in a journey to the Afterlife such as the one staged. Several references to the Eleusinian Mysteries are also discussed in the parodos, as many authors have seen in Iacchus an epiclesis of Dionysus. The study of the hymns to Iacchus in the parodos and of several parallels of the period makes it possible to ascertain that he is not identified with Dionysus, but that he is an Eleusinian god. It is concluded that the mentions of the Dionysian festivals are intended to emphasize the civic aspect of the god and his patronage of the theatre, a vital institution for enlivening the Athenians at a time of serious crisis such as the end of the Peloponnesian War.