This chapter explains how white supremacy evolved and adapted after the US Civil War and the abolition of slavery across the British Empire. Rather than weakening, white power structures found new ways to maintain racial hierarchies through scientific racism, Social Darwinism, and eugenics. These scientific frameworks provided intellectual justification for continued oppression while appearing objective and dispassionate. The period saw the rise of immigration restrictions, voter suppression, and systematic segregation across English-speaking societies, all designed to preserve white political and economic power. New “race perils” reflected white anxieties about demographic change, while eugenics aimed to protect racial “purity” through sterilization programs and anti-miscegenation laws. Particularly significant was the denial of capital accumulation to nonwhites through housing discrimination, job discrimination, and business restrictions. Although many voices challenged these racist theories and practices as false and cynical, they were consistently overpowered by institutional forces desperate to maintain white supremacy.