Donatism is a Christian sect within the Roman province of Africa that flourishes in the fourth and fifth centuries.

It had its roots in the social pressures among the long-established Christian community of Roman North Africa (present-day Tunisia and Algeria), during the persecutions of Christians under Diocletian.

The Donatists (named for the Berber Christian bishop Donatus Magnus) are members of a schismatic church not in communion with the churches of the Catholic tradition in Late Antiquity.Donatism wis an indirect outcome of Diocletian's persecutions.

The governor of Africa had been lenient towards the large Christian minority under his rule during the persecutions.

He was satisfied if Christians handed over their Scriptures as a token repudiation of their faith.

Some Christians acceded to this convenient action.

When the persecutions came to an end, however, they were branded traditores, "traitors" by the zealous, mostly from the poorer classes.

Like the Novatianist schism of the previous century, the Donatists were rigorists, holding that the church must be a church of "saints," not "sinners," and that sacraments, such as baptism, administered by traditores were invalid.

In 313, a commission appointed by Pope Miltiades finds against the Donatists, but they continue to exist, viewing themselves, and not the Catholic Church, as the "true Church," the only one with "valid sacraments."

Because of their association with the Circumcellions, they bring upon themselves repression by the imperial authorities, but they draw upon African regional sentiment, while the Catholic party has the support of Rome.

They are still a force at the time of Saint Augustine of Hippo at the end of the fourth century, and disappear only after the Arab conquest of the 7th–8th century.