Matris Magnae referred to festivals dedicated to the Magna Mater (Great Mother) Cybele, whose cult Rome officially adopted during the Second Punic War. These celebrations emphasized maternal divine power, featured ecstatic music and dance, and included the taurobolium (bull sacrifice). Eunuch priests called Galli served the goddess with fervent devotion. In poetry, Matris Magnae evokes maternal divinity, religious ecstasy, and Eastern influence, appearing in works exploring the Great Mother archetype, castration imagery, exotic ritual, and Rome's integration of Phrygian worship that both fascinated and disturbed traditional Roman sensibilities.

Matris Magnae emphasizes Cybele's maternal aspects as the Great Mother, stressing her nurturing and protective functions. The festival's focus on Cybele's maternity distinguishes it from celebrations emphasizing her wild or ecstatic characteristics. Understanding Matris Magnae helps illuminate Cybele's complex nature in Roman religion and her appeal as universal mother goddess. The festival demonstrates how Romans adapted Phrygian goddess worship to emphasize aspects resonating with Roman maternal values.