Historically, the study of race by natural and social scientists involved categorizing different groups of people and arranging them hierarchically. Such classification gave ideological support to slavery, colonialism and other forms of racial domination. This chapter critically examines the important contributions made by social and cultural theorists to the study of race and ethnicity, focusing primarily on developments in thought and argument since the Second World War. It concludes that both concepts remain relevant to our understanding of major social divisions and to the structuring of society, and to our understanding of the globalizing conditions of the twenty-first century. Though anti-racist struggle has ebbed and flowed, it has been re-energized through movements such as Black Lives Matter, which became a truly global movement in 2020, sparked by the brutal slaying of African American George Floyd by police in Minneapolis. Despite the COVID-19 pandemic, and dire warnings from public health officials, protest exploded on the streets of cities throughout the world. New voices have risen calling for real action to dismantle white supremacy, white privilege and structural racism. Race has surged back as a key concept for understanding contemporary society.