This article explores Eugene V. Debs’s experiences at the Moundsville prison and the federal penitentiary in Atlanta (1919–1921). It looks at his relationships with other inmates and his supporters outside of prison and examines the effects prison life had on Debs and his ideology. Most importantly, it closely examines his only book-length work: his prison memoir, Walls and Bars. It explores Debs’s critique of the prison system, the jailing of drug addicts, and the interconnectedness of capitalism and the penitentiary system.