In 451 CE, the Council of Chalcedon was called to assert the preeminence of orthodox Catholic doctrine against the heresy of men who refused what we now refer to as the Definition of Faith, or the belief in Jesus Christ as both man and divine spirit during his lifetime. The establishment of Council of Chalcedon in 451 marked a defining moment in the Christological controversies that tore apart the church of the Eastern Roman Empire in the fifth and sixth centuries. Theological division, political rivalry and sectarian violence combined to produce what ultimately became separate Chalcedonian and Miaphysite churches, a split that persists to this day. Chalcedon is typically remembered in terms of its doctrinal product, the Definition of Faith. But surprisingly, little attention has been devoted to examining the process by which that result was reached, the day-by-day deliberation of the council as revealed in its documentary acts. The Acts of the fifth-century councils offer us a type of source material extremely rare in the ancient world, the verbatim transcripts of a deliberative assembly in operation.The Roman Senate, which met continuously for nearly a thousand years, has left almost no direct record of its proceedings and is known to us mainly from later sources often writing several generations after the events they claim to describe. The church councils show us bishops and imperial officials grappling with issues ranging from high theology to ecclesiastical discipline to episcopal corruption. The Acts offer a unique demonstration of the convergence between the concerns of church leaders and the and imperial court officials of the secular government. This authoritative text fills an important gap in Church History and Ecumenism. It is essential reading for scholars studying this period.