Throughout the course of the 19th century, the definition of who the criminal man was influenced the way he was treated. Whether theorists could identify the criminal along biological, social or psychological terms influenced prison policy on how to turn crime doers away from their lives of evil. In fact, reform was the ultimate goal of the 19th century penitentiary. It was for this reason that policy makers were so adamant in aligning the way criminals were treated with their perceptions of how ‘the criminal’ came to be. If the criminal is simply, as classical theorists would suggest, a rational man, then to force him to contemplate his actions will reform him. If, however, he is biologically pre-disposed to commit crimes, harsher reform strategies need to be taken. We will analyze those strategies taken within the context of the New York State penitentiary, Sing Sing Prison and its predecessor Auburn Prison.