When Lyndon Johnson succeeded John Kennedy as president he accepted Kennedy's agenda, but his electoral victory in 1964 freed him to set his own. His agenda included declaring the War on Poverty and striving to create the Great Society. Measures he pushed through Congress had sweeping social implications. The 1964 Civil Rights Act prohibited discrimination in public accommodations, public education, and employment; the women's rights movement made an important gain when a congressman, attempting to kill the bill, inserted the word "sex" into the list of grounds on which discrimination would be prohibited. The 1965 Voting Rights Act sought to remove barriers that prevented blacks from voting, and the 1968 Open Housing Act prohibited racial discrimination in housing and jury service. Other Great Society measures included Medicare, federal support for schools at all levels, programs for improving housing, increases in social security, reform of immigration laws, programs for research and treatment of physical and mental illnesses and construction of facilities for these purposes, federal support for the arts and humanities, highway safety and beautification programs, pollution controls, and consumer protection laws.

While pursuing this agenda, Johnson also had the controversial Vietnam War on his hands. The more deeply he led the United States into it, the more elusive victory became. Protests against his policies increased in intensity. By 1968 he was ready to turn the war in Vietnam over to his successor, Richard Nixon, under whom divisions over war policy continued. Protests on campuses were most intense following the killing of four students by National Guardsmen's bullets at Kent State University on May 4, 1970. Meanwhile, about 11 million of the almost 27 million men of draft age were drafted or enlisted. Some of the rest were exempted for physical reasons, some had deferments to attend college, and about 50,000 exiled themselves to Canada and other places. Altogether, 2.7 million Americans served in Vietnam, 300,000 were wounded, and 58,000 died. More than one in six who served received less-than-honorable discharges because of desertion, drug use at the front, or voicing antiwar sentiment.