From the mid-nineteenth century to the Gilded Age, Catharine Beecher and other American social reformers combined natural theology and evangelism to instruct their audiences how to lead healthy, virtuous, and happy lives. Worried about the consequences of urbanization, industrialization, unstable sexual and gender roles, and immigration, these “Christian physiologists” provided prescriptive scientific advice for hygiene and personal conduct based on the traditional norms of white, middle-class, Protestant domesticity. According to Beecher and her counterparts, the biosocial reproduction of ideal American households (...) promised to reverse the degeneration of men and women across the country and to ensure the long-term vitality of their children. Using evidence from Beecher, Harriet Beecher Stowe, Charlotte Perkins Gilman, and other nineteenth-century writers, I investigate the methods and aims of Christian physiology along with its relationships to natural theology, Darwinian feminism, and other reform movements. I also analyze how Beecher and her successors employed concepts including the machine, the tissue, the cell, and the germ to justify their conclusions about the optimal structure and functions of American society. Overall, I demonstrate how these actors leveraged the body and the family as mechanisms to produce healthy parents, children, and communities for an ailing nation. (shrink)