Organismal biology is an established scholarly discipline, yet its origins have been obscured by Darwinian histories of biology. Emerging over the late nineteenth and early twentieth centuries, organismal biology stemmed not from the work of Darwin and his circle, but was inspired by Romantic natural philosophers, embryologists, anatomists and physiologists. Esposito presents a historiography of organicist and holistic thought through an examination of the work of leading biologists from Britain (Haldane, Thompson, Russell and Woodger) and America (Ritter, Child, Lillie and Just). He shows how this work relates to earlier Romantic thought and sets it within the wider context of the history and philosophy of the life sciences.