In this chapter I discuss attitudes toward sex and gender categories. I begin by distinguishing between egalitarian and traditional gender-role attitudes. Then, I move to considering attitudes toward gender in terms of affect (sexism), cognition (stereotyping), and behavior (discrimination). Research on sexism has distinguished between traditional sexism and modern sexism, as well as between hostile and benevolent sexism. Although hostile sexism reflects a negative attitude, and benevolent sexism reflects a positive attitude, the two are positively correlated, reflecting their connection to the view of women as less competent than men. I also discuss attitudes toward LGBT persons. Despite more positive attitudes toward LGBT persons, stereotypes persist. However, there is greater recognition of the intersectionality of gender stereotypes with other categories, such as race, ethnicity, gender identity, and sexual orientation. Stereotyping can lead to a self-fulfilling prophecy, whereby our beliefs influence others’ behavior to confirm our beliefs. Stereotype-inconsistent behavior can lead to negative repercussions, or backlash, which serve to reinforce stereotype-congruent behavior. Some attention is paid to sex discrimination, including discrimination against LGBT persons, but this is elaborated on in later chapters (e.g., Chapter 12).