The story goes that all thoroughbreds, unless bred fraudulently, descend from three foundation sires taken to Great Britain from the Levant, the Maghreb, and Arabia in the late-seventeenth and early-eighteenth centuries. That’s just a story, though, and a breed is more a term of art than a scientific fact. Historian William Cronon implored environmental historians to tell “stories about stories about nature.” The stories people told about thoroughbreds over the breed’s three-century history illuminate unspoken assumptions of their society, assumptions about how inheritance works, about how to organize labor, and about how humans see themselves in their environments. What, for instance, is inherited alongside genes? The language of inheritance is lacking. It conflates the biological, the inevitable, with the social. Inheritance is a social process as well as a biological one. Humans tell stories to make sense of the things carried on from the past; and what we mean when we say something is inherited, includes both the social and the biological. The stories about thoroughbreds are powerful precisely because they make the social, the messy, contingent, and constructed past, seem natural. Thoroughbred breeders narrated their animals in various ways using pedigrees, landscapes, animal bodies, standards, and DNA analysis to tell their stories. I argue that a comprehensive understanding of inheritance must accommodate the discourses that informed breeding decisions. These discourses, as much as genes, had real, material effects on both animals and people. As a category, the thoroughbred has remained more or less constant for three hundred years allowing historians to identify how the discourse around thoroughbreds changed over time, place, and political economic regime. My dissertation begins in the desert outside Aleppo at the turn of the eighteenth century in what was then the Ottoman Empire. British traders working for the Levant Company brought Arabian horses back to Great Britain where they were put to native mares to produce exceptional running horses that became totems of the restored monarchy. When Virginia cavaliers sent their sons to Cambridge for university, the young men grew found of horse racing and shipped their favorite stallions back to the colonies. In Kentucky, thoroughbred owners found a landscape with calcium-rich soil amenable to raising horses for racing. The American Civil War destroyed the South’s horse country, and industrial capitalists from the North adopted thoroughbred racing as their preferred pastime. The new political economy of horse racing prompted a standardization of the breed that turned the animals into fungible commodities. Standardization expanded the geography of horse racing during the Gilded Age, and California’s robber barons struggled to turn their arid latifundia into western simulacra of Kentucky’s Bluegrass Region. With the rediscovery of Mendelian genetics in 1900, racialist thinkers seized upon the thoroughbred to promote ideas of eugenics and racial progress. By the 1980s, thoroughbred racing had been securitized and investors turned to the emerging science of genomics to guide their investments, using thoroughbred horses to promulgate an updated version of genetic determinism. This dissertation follows the thoroughbred breed from its foundation sires in the eighteenth-century Ottoman Empire to the modern animals competing in a globalized horse racing industry. In eight chapters, I investigate thoroughbreds as they fanned out from Great Britain to breeding farms in countries as far flung as Argentina and Zimbabwe. Each chapter focuses on a place and a theme. Chapter One, set in the Ottoman Empire, examines the technology of the animal pedigree adopted from Bedouin traders. British breeders used the pedigree and put a premium on inherited characteristics. Chapter Two identifies the political meaning of breeding as the thoroughbred developed in Great Britain. The thoroughbred became synonymous with the restored monarchy and an emblem of Britishness despite the horses’ obvious Eastern origins. Chapter Three studies the role of the breed in defining a landscape, in particular Kentucky’s Bluegrass Region. Thoroughbred owners in Kentucky’s Bluegrass used their property, both animal and human, to create a landscape that both supported equine reproduction and celebrated the noble animals. Chapter Four follows the adoption of thoroughbred horses as a new form of capital for the American industrial class. Following the Civil War, American industrialists used horses as banks of stored capital and as cultural capital that established the industrialists on the same footing as European aristocrats. Chapter Five highlights the intellectual work necessary to creating thoroughbreds as banks of stored capital. As the scope and scale of raising thoroughbreds increased, owners needed guarantee that a thoroughbred from California was the same as one from New York. Chapter Six moves the narrative to California and shows how that state’s robber barons used thoroughbreds to imaginatively express their vision of industrial capitalism in the western United States. Chapter Seven argues that the elite culture of thoroughbred racing provided racialist thinkers an animal to adopt as experimental animals that purportedly exhibited biological progress. Thoroughbreds, with hundreds of years of pedigrees and breeding data, provided the necessary raw materials for racial scientists. Chapter Eight shows how resilient this narrative of biological progress has been. During the 1980s, increasing capital investment required assurances of success. Investment bankers looked to academic geneticists to provide value for their investments. New genetic testing led to a retrenchment of biological determinism. The stories people told about thoroughbreds—they were myths, really—still shape the industry today and trickle down and inform popular conceptions of inheritance. My dissertation argues that the stories people tell about their livestock have both material and intellectual consequences. Believing that thoroughbreds were noble, gendered, and British by birth justified all kinds of behaviors from land use decisions to scientific racism. From a biological perspective, reproduction is always conservative. Reproduction preserves genes from one generation to another. By looking at the stories people told about thoroughbreds, I show how historical actors used animal husbandry to reproduce and justify the status quo.