Jack Hood Vaughn is sworn in as United States Ambassador to Panama at the State Department on April 13, 1964. Vaughn, who succeeded R. Sargent Shriver as the second director of the Peace Corps, died Oct. 29 at his home in Tucson. He was 92. (AP)

Jack Hood Vaughn, a U.S. diplomat who succeeded R. Sargent Shriver as director of the Peace Corps in 1966 and spent three years guiding the organization to its peak of volunteer enrollment, died Oct. 29 at his home in Tucson. He was 92.

He had an aggressive, undiagnosed cancer, said his wife Margaret Vaughn.

Mr. Vaughn, a specialist in Latin America and an outspoken advocate of goodwill diplomacy, held influential State Department jobs during the Kennedy, Johnson and Nixon administrations but was perhaps best known as director of the Peace Corps.

When he took over, the service organization had just over 10,000 volunteers in 46 countries, and they were performing tasks such as beekeeping in Africa and accounting work in Central Asia, Time magazine reported.

During Mr. Vaughn’s tenure, enrollment rose to more than 15,500 volunteers in more than 50 countries, according to the Peace Corps.

One of the chief hurdles in recruitment, Mr. Vaughn found, was “parental distress.” He prevailed on worried mothers to let their children decide whether to pursue the Peace Corps, admonishing the women that they had “nothing to lose but their apron strings.”

During the Vietnam War, critics of the social service program charged that some volunteers used Peace Corps service to obtain a draft deferment. Mr. Vaughn defended the volunteers in 1966, saying they were “second to no other Americans. . . . I am ready to dispute anyone on that point, including 4,000 draft boards if it comes to that.”

As an administrator, Mr. Vaughn was praised for what The Washington Post described as his “Pentagon-type cost-analysis procedures.”

“It costs less money to make peace than war,” he once told the House Foreign Affairs Committee during budgetary hearings. “But it still costs a lot.”

Mr. Vaughn was an aid worker in the West African country of Senegal when he first met Shriver, the Kennedy in-law and founding director of the Peace Corps. In 1961, Shriver tapped Mr. Vaughn as head of operations in Latin America for the nascent service organization.

Three years later, President Lyndon B. Johnson nominated Mr. Vaughn to be ambassador to Panama. After a year in that post, he became assistant secretary of state for inter-American affairs and one of President Johnson’s most influential envoys in Latin America. From 1969 to 1970, Mr. Vaughn served as ambassador to Colombia.

Mr. Vaughn, a registered Republican, left the State Department in 1970, reportedly because he felt the Nixon administration officials had neglected Latin America as they focused on other parts of the world.

He said he was proud to have been known as the “peasant ambassador,” a moniker given to him because of his hands-on approach to diplomacy.

Jack Hood Vaughn was born Aug. 18, 1920, in Columbus, Mont. He said he was the son of a cowboy.

He grew up in Michigan and graduated from high school late — at 20, Time magazine reported — because he spent much of his adolescence in the boxing ring. A featherweight, he called himself Johnny Hood and amassed 149 victories in 172 amateur and professional fights and was never knocked out, Time reported.

Mr. Vaughn received a bachelor’s degree in romance languages in 1943 and a master’s degree in economics in 1947, both from the University of Michigan. During World War II, he served in the Marines in the Pacific and participated in the Okinawa campaign.

In the early years of his career, he worked in Latin America and Africa as an information officer and aid coordinator.

After his government service, he served in positions that included president of the National Urban Coalition, president of the Planned Parenthood Federation of America and director of international programs for the Children’s Television Workshop, which was created to produce “Sesame Street.” He retired as chairman of Ecotrust, an environmental organization he helped found in Portland, Ore.

His first marriage, to the former Joanne Smith, ended in divorce. Survivors include his wife of 42 years, Margaret Weld Vaughn of Tucson; two children from his first marriage, Kathryn Vaughn Tolstoy of Montreal and Carol Vaughn of Quebradas, Costa Rica; two children from his second marriage, Jack Hood Vaughn Jr. of New York City and Jane Constantineau of Virginia Beach; three sisters; and two grandchildren.

As Peace Corps director, Mr. Vaughn argued that host nations were not the only beneficiaries of service by American volunteers. “Our nation,” he said, “will be the better for it.”