The ostensible and official purpose of the Ara Pacis was to celebrate the return of Augustus and the coming of the Pax Augusta. Augustus may have purposefully made the monument relatively modest to reassure other magistrates that they would still have room in the new principate to exercise their own fame and self-fulfillment (Zanker 160).

After being dedicated, the Ara Pacis was used by the Vestal Virgins, magistrates, and priests on January 30 (Livia's birth date) and July 4 (the date of the dedication of the Ara Pacis) to make sacrifices in the name of Peace.

Augustus refused himself another triumph in favor of the dedication of the Ara Pacis. Bowman suggests this reinforces the notion that Augustus’ closing of the doors of Janus' temple in 25 BC, following the end of the civil wars, was premature in that it required an additional 12 years to fully subjugate and pacify the people of Spain and Gaul (Bowman 166). Augustus may have felt it necessary to construct an altar dedicated to peace to reassure the people that the peace won through civil war was well worth the bloodshed and hardship. The Ara Pacis, then, was only Augustus' propaganda to reinforce his triumphs granted earlier.