Ambassadors in Chains is a study of four Christians from different eras who were imprisoned for taking stands against the policies and practices of their respective governments: Perpetua of Carthage (181-203), Maximus the Confessor (580-662), Thomas More (1478-1535), and Martin Luther King Jr. (1929-1968). All four wrote about the religious convictions for which they were incarcerated and those by means of which they endured the sufferings of imprisonment and successfully resisted the efforts of the state to force their capitulation. These four prisoners of conscience can serve as models of principled Christian resistance in our own time of growing authoritarianism and religious nationalism. This work could serve as a textbook for courses on social ethics, penology, or prison ministry at Christian colleges, universities, or theological seminaries.