Sozomen was a Christian historian of the 5th century CE. He was born in Bethelia, near Gaza, into a wealthy family that had converted from paganism. After training in law and rhetoric, he worked as a lawyer in Palestine before moving to Constantinople around 440 CE. The exact dates of his birth and death are unknown.

He is known for a single surviving work, the Historia Ecclesiastica (Ecclesiastical History). This nine-book history covers the Christian church from 324 to 439 CE. It was written in Constantinople and dedicated to Emperor Theodosius II.

Sozomen’s work is a major source for the history of the early church. He followed the model of earlier historians like Eusebius and used the work of his contemporary Socrates Scholasticus as a primary source. According to modern scholars, his history is notable for its detailed coverage of the rise of monasticism, reflecting his family’s background and regional interests. While his narrative often parallels that of Socrates, he aimed for a more polished literary style and incorporated additional documents and traditions. Academics note that his history provides a crucial perspective on the theological disputes and growth of the church, though they recognize his bias in favor of Nicene orthodoxy and his tendency to smooth over conflicts.