This chapter is about the origins of anti-Black racism in the United States. It describes two separate but related processes. The first process involves historical events, of which slavery is the most important. In addition to systemic exploitation and degradation of enslaved people, slavery produced beliefs that enslaved people were inferior human beings. Reinforcing these beliefs was scientific racism – supposedly scientific theories that purported to prove the innate inferiority of Black people. Even after slavery ended, economic competition, racist laws, and social norms created social and economic disadvantages for Black people. The second process involves the ways humans think about the people they encounter. Humans place themselves and other people in social groups largely based on physical characteristics, particularly those that society considers to be important. Perceived race is a major determinant of how people socially categorize others, which forms the psychological foundation for racial biases at both the conscious and nonconscious levels. Thus, even in the absence of malevolent intent, it is likely that people will develop negative racial beliefs and feelings. These biases lead to the tendency of White Americans to justify the disadvantages experienced by Black Americans by attributing them to inherent defects in Black people.