During the war, Buckley’s family took in the future British historian Alistair Horne (son of Sir Allan Horne) as a child war evacuee. He and Buckley remained lifelong friends. They both attended the Millbrook School in Millbrook, New York, graduating in 1943. Buckley was a member of the American Boys’ Club for the Defense of Errol Flynn (ABCDEF) during Flynn’s trial for statutory rape in 1943. At Millbrook, Buckley founded and edited the school’s yearbook, The Tamarack; this was his first experience in publishing. When Buckley was a young man, his father was an acquaintance of libertarian author Albert Jay Nock. William F. Buckley Sr., encouraged his son to read Nock’s works.

Buckley attended the National Autonomous University of Mexico (or UNAM) in 1943. The following year, upon his graduation from the US Army Officer Candidate School (OCS), he was commissioned as a second lieutenant in the United States Army. In his book Miles Gone By, he briefly recounts being a member of Franklin Roosevelt’s honor guard upon Roosevelt’s death. He served stateside throughout the war at Fort Benning, Georgia; Fort Gordon, Georgia; and Fort Sam Houston, Texas.

This feud continued the next year in Esquire magazine, which commissioned essays from Buckley and Vidal on the incident. Buckley’s essay “On Experiencing Gore Vidal” was published in the August 1969 issue. In September, Vidal responded with his own essay, “A Distasteful Encounter with William F. Buckley”. In it Vidal strongly implied that, in 1944, Buckley’s unnamed siblings and possibly Buckley himself had vandalized a Protestant church in their Sharon, Connecticut, hometown after the pastor’s wife sold a house to a Jewish family. He also implied that Buckley was homosexual and a “racist, antiblack, anti-Semitic and a pro-crypto Nazi.” Buckley sued Vidal and Esquire for libel; Vidal countersued Buckley for libel, citing Buckley’s characterization of Vidal’s novel Myra Breckenridge as pornography. After Buckley received an out-of-court settlement from Esquire, he dropped the suit against Vidal. Both cases were dropped, with Buckley settling for court costs paid by Esquire, which had published the piece, while Vidal, who did not sue the magazine, absorbed his own court costs. Neither paid the other compensation. Buckley also received an editorial apology from Esquire as part of the settlement.

At the end of World War II in 1945, Buckley enrolled at Yale University, where he became a member of the secret Skull and Bones society and was a masterful debater. He was an active member of the Conservative Party of the Yale Political Union, and served as Chairman of the Yale Daily News and as an informer for the FBI. Buckley studied political science, history, and economics at Yale, graduating with honors in 1950. He excelled on the Yale Debate Team; under the tutelage of Yale professor Rollin G. Osterweis, Buckley honed his acerbic style.

In 1950, Buckley married Patricia Aldyen Austin “Pat” Taylor (1926–2007), daughter of Canadian industrialist Austin C. Taylor. He met Taylor, a Protestant from Vancouver, British Columbia, while she was a student at Vassar College. She later became a prominent fundraiser for such charitable organizations as the Memorial Sloan Kettering Cancer Center, the Institute of Reconstructive Plastic Surgery at New York University Medical Center and the Hospital for Special Surgery. She also raised money for Vietnam War veterans and AIDS patients. On April 15, 2007, Pat Buckley died at age 80 of an infection after a long illness. After her death, Buckley seemed “dejected and rudderless”, according to friend Christopher Little.

The release of his first book, God and Man at Yale, in 1951 was met with some specific criticism pertaining to his Catholicism. McGeorge Bundy, dean of Harvard at the time, wrote in The Atlantic that “it seems strange for any Roman Catholic to undertake to speak for the Yale religious tradition”. Henry Sloane Coffin, a Yale trustee, accused Buckley’s book of “being distorted by his Roman Catholic point of view” and stated that Buckley “should have attended Fordham or some similar institution”.

In 1951, along with many other Ivy League alumni, Buckley was recruited into the Central Intelligence Agency (CIA); he served for two years, including one year in Mexico City working on political action for E. Howard Hunt, who was later jailed for his part in the Watergate affair. The two officers remained lifelong friends. In a November 1, 2005, column for National Review, Buckley recounted that while he worked for the CIA, the only CIA employee he knew was Hunt, his immediate boss. While stationed in Mexico, Buckley edited The Road to Yenan, a book by Peruvian author Eudocio Ravines.

Buckley’s first book, God and Man at Yale, was published in 1951. Offering a critique of Yale University, Buckley argued in the book that the school had strayed from its original mission. Critics viewed the work as miscasting the role of academic freedom. Buckley himself credited the attention the book received in the media to the “Introduction” written by John Chamberlain, saying that it “chang[ed] the course of his life” and that the famous Life magazine editorial writer had acted out of “reckless generosity.” William F. Buckley Jr. was referred to in the novel The Manchurian Candidate by Richard Condon in 1959 as “that fascinating younger fellow who had written about men and God at Yale.”

In 1954, Buckley and his brother-in-law L. Brent Bozell Jr. co-authored a book, McCarthy and His Enemies. Bozell worked with Buckley at The American Mercury in the early 1950s when it was edited by William Bradford Huie. The book strongly defended Senator Joseph McCarthy as a patriotic crusader against communism. The book asserted that “McCarthyism … is a movement around which men of good will and stern morality can close ranks.” Buckley edited The American Mercury in 1951 and 1952, but left after perceiving newly emerging anti-Semitic tendencies in the magazine.

Buckley founded National Review in 1955 at a time when there were few publications devoted to conservative commentary. He served as the magazine’s editor-in-chief until 1990. During that time, National Review became the standard-bearer of American conservatism, promoting the fusion of traditional conservatives and libertarians. Examining postwar conservative intellectual history, Kim Phillips-Fein writes:

In 1960, Buckley helped form Young Americans for Freedom (YAF). The YAF was guided by principles Buckley called “The Sharon Statement”. Buckley was proud of the successful campaign of his older brother, Jim Buckley, on the Conservative Party ticket to capture the US Senate seat from New York State held by incumbent Republican Charles Goodell in 1970, giving very generous credit to the activist support of the New York State chapter of YAF. Buckley served one term in the Senate, then was defeated by Democrat Daniel Patrick Moynihan in 1976.

In 1962, Buckley denounced Robert W. Welch Jr. and the John Birch Society in National Review as “far removed from common sense” and urged the Republican Party to purge itself of Welch’s influence.

Buckley’s column On the Right was syndicated by Universal Press Syndicate beginning in 1962. From the early 1970s, his twice-weekly column was distributed regularly to more than 320 newspapers across the country. He authored 5,600 editions of the column, which totaled to over 4.5 million words.

In 1962, Edgar Smith, who had been sentenced to death for the murder of 15-year-old high school student Victoria Ann Zielinski, began a correspondence with Buckley from death row. As a result of the correspondence, Buckley began to doubt Smith’s guilt. Buckley later said the case against Smith was “inherently implausible”. An article by Buckley about the case, published in Esquire in November 1965, drew national media attention:

When he first met author Ayn Rand, according to Buckley, she greeted him with the following: “You are much too intelligent to believe in God.” In turn, Buckley felt that “Rand’s style, as well as her message, clashed with the conservative ethos”. He decided that Rand’s hostility to religion made her philosophy unacceptable to his understanding of conservatism. After 1957, he attempted to weed her out of the conservative movement by publishing Whittaker Chambers’s highly negative review of Rand’s Atlas Shrugged. In 1964, he wrote of “her desiccated philosophy’s conclusive incompatibility with the conservative’s emphasis on transcendence, intellectual and moral,” as well as “the incongruity of tone, that hard, schematic, implacable, unyielding, dogmatism that is in itself intrinsically objectionable, whether it comes from the mouth of Ehrenburg, Savonarola—or Ayn Rand.” Other attacks on Rand were penned by Garry Wills and M. Stanton Evans. Nevertheless, Burns argues, her popularity and her influence on the Right forced Buckley and his circle into a reconsideration of how traditional notions of virtue and Christianity could be integrated with all-out support for capitalism.

In 1965, Buckley ran for mayor of New York City as the candidate for the new Conservative Party. He ran to restore momentum to the conservative cause in the wake of Goldwater’s defeat. He tried to take votes away from the relatively liberal Republican candidate and fellow Yale alumnus John Lindsay, who later became a Democrat. Buckley did not expect to win; when asked what he would do if he won the race, he responded, “Demand a recount.” He used an unusual campaign style. During one televised debate with Lindsay, Buckley declined to use his allotted rebuttal time and instead replied, “I am satisfied to sit back and contemplate my own former eloquence.”

Politico indicates that during the administration of Lyndon B. Johnson, Buckley’s writing grew more accommodating toward the civil rights movement. In his columns, he “ridiculed practices designed to keep African Americans off the voter registration rolls”, “condemned proprietors of commercial establishments who declined service to African Americans in violation of the recently enacted 1964 Civil Rights Act”, and showed “little patience” for “Southern politicians who incited racial violence and race-baited in their campaigns”. However, Buckley continued to downplay structural racism and place a large amount of blame for lack of economic growth on the black community itself, most prominently during a highly publicized 1965 debate at the Cambridge Union with African-American writer James Baldwin in which Baldwin carried the floor. In the late 1960s, however, Buckley disagreed with segregationist George Wallace of Alabama; he debated against Wallace’s segregationist platform on a January 1968 episode of Firing Line.

Buckley’s article brought renewed media interest in Hommell, who Smith claimed was the real killer. In 1971 there was a retrial. Smith took a plea deal, and was freed from prison that year. Buckley interviewed him on Firing Line soon thereafter.

In July 1971, Buckley assembled a group of conservatives to discuss some of Nixon’s domestic and foreign policies that the group opposed. In August 1969, Nixon had proposed and later attempted to enact welfare legislation known as the Family Assistance Plan (FAP), which would establish a national income floor of $1,600 per year for a family of four. On the international front he negotiated arms talks with the Soviet Union and initiated relations with China, which Buckley, as a hawk and anti-communist, opposed. The group, known as the Manhattan Twelve, included National Review’s publisher William A. Rusher and editors James Burnham and Frank Meyer. Other organizations represented were the newspaper Human Events, The Conservative Book Club, Young Americans for Freedom, and the American Conservative Union. On July 28, 1971, they published a letter announcing that they would no longer support Nixon. The letter said, “In consideration of his record, the undersigned, who have heretofore generally supported the Nixon Administration, have resolved to suspend our support of the Administration.”

Nonetheless, in 1973, the Nixon Administration appointed Buckley to serve as a delegate to the United Nations, about which Buckley later wrote a book. In 1981, Buckley informed President-elect (and personal friend) Ronald Reagan that he would decline any official position offered to him. Reagan jokingly replied that was too bad, because he had wanted to make Buckley ambassador to (then Soviet-occupied) Afghanistan. Buckley replied that he was willing to take the job but only if he were to be supplied with “10 divisions of bodyguards”.

In 1975, Buckley recounted being inspired to write a spy novel by Frederick Forsyth’s The Day of the Jackal: “… If I were to write a book of fiction, I’d like to have a whack at something of that nature.” He went on to explain that he was determined to avoid the moral ambiguity of Graham Greene and John le Carré. Buckley wrote the 1976 spy novel Saving the Queen, featuring Blackford Oakes as a rule-bound CIA agent, based in part on his own CIA experiences. Over the next 30 years, he would write another ten novels featuring Oakes. New York Times critic Charlie Rubin wrote that the series “at its best, evokes John O’Hara in its precise sense of place amid simmering class hierarchies”. Stained Glass, second in the series, won a 1980 National Book Award in the one-year category Mystery (paperback).

In 1976, five years after being released from prison, Smith attempted to murder another woman in San Diego, California. After witnesses corroborated the story of Lisa Ozbun, who survived being stabbed by Smith, he was sentenced to life in prison. He admitted at the trial that he had in fact also murdered Zielinski. Buckley subsequently expressed great regret at having believed Smith and supported him.

In the late 1960s, Buckley joined the Board of Directors of Amnesty International USA. He resigned in January 1978 in protest over the organization’s stance against capital punishment as expressed in its Stockholm Declaration of 1977, which he said would lead to the “inevitable sectarianization of the amnesty movement”.

Buckley began writing on computers in 1982, starting with a Zenith Z-89. According to his son, Buckley developed an almost fanatical loyalty to WordStar, installing it on every new PC he got despite its growing obsolescence over the years. Buckley used it to write his last novel, and when asked why he continued using something so outdated, he answered “They say there’s better software, but they also say there’s better alphabets.”

In 1988, Buckley helped defeat liberal Republican Senator Lowell Weicker in Connecticut. Buckley organized a committee to campaign against Weicker and endorsed his Democratic opponent, Connecticut Attorney General Joseph Lieberman.

In 1991, Buckley received the Presidential Medal of Freedom from President George H. W. Bush. Upon turning 65 in 1990, he retired from the day-to-day running of the National Review. He relinquished his controlling shares of National Review in June 2004 to a pre-selected board of trustees. The following month, he published the memoir Miles Gone By. Buckley continued to write his syndicated newspaper column, as well as opinion pieces for National Review magazine and National Review Online. He remained the ultimate source of authority at the magazine and also conducted lectures and gave interviews.

In his 1997 book Nearer, My God, Buckley condemned what he viewed as “the Supreme Court’s war against religion in the public school” and argued that Christian faith was being replaced by “another God … multiculturalism”. As an adult, Buckley regularly attended the Tridentine Mass in Connecticut. He disapproved of the liturgical reforms following the Second Vatican Council. Buckley also revealed an interest in the writings and revelations of the 20th Century Italian writer Maria Valtorta. In his spiritual memoir, Buckley reproduced Valtorta’s detailed accounts of Jesus Christ’s crucifixion; these accounts were based on Valtorta’s visionary experiences of Christ and the mystical revelations she recorded in her book The Poem of the Man-God.

The feud was reopened in 2003 when Esquire republished the original Vidal essay as part of a collection titled Esquire’s Big Book of Great Writing. After further litigation, Esquire agreed to pay $65,000 to Buckley and his attorneys, to destroy every remaining copy of the book that included Vidal’s essay, to furnish Buckley’s 1969 essay to anyone who asked for it, and to publish an open letter stating that Esquire’s current management was “not aware of the history of this litigation and greatly [regretted] the re-publication of the libels” in the 2003 collection.

Buckley later said he wished National Review had been more supportive of civil rights legislation in the 1960s. He grew to admire Martin Luther King, Jr. and supported the creation of Martin Luther King, Jr. Day. In 2004, Buckley told Time, “I once believed we could evolve our way up from Jim Crow. I was wrong. Federal intervention was necessary.” The same year, he endeavored to clarify his earlier comments on race, saying: “[T]he point I made about white cultural supremacy was sociological.” Buckley also linked his usage of the word advancement to its usage in the name NAACP, saying that “[the] call for the ‘advancement’ of colored people presupposes they are behind. Which they were, in 1958, by any standards of measurement.”

In a March 18, 1986, New York Times op-ed, Buckley addressed the AIDS epidemic. Calling it “a fact” that AIDS is “the special curse of the homosexual,” he argued that people infected with HIV should marry only if they agreed to sterilization and that universal testing—led by insurance companies, not the government—should be mandatory. Most controversially of all, he wrote, “Everyone detected with AIDS should be tattooed in the upper forearm, to protect common-needle users, and on the buttocks, to prevent the victimization of other homosexuals.” The piece led to much criticism; some gay activists advocated boycotting Patricia Buckley’s fund-raising efforts for AIDS. William Buckley later backtracked from the piece, but in 2004 he told The New York Times Magazine, “If the protocol had been accepted, many who caught the infection unguardedly would be alive. Probably over a million.”

Buckley was an advocate for the legalization of marijuana and some drug legalization as early as his 1965 candidacy for mayor of New York City. He wrote a pointed pro-marijuana legalization piece for National Review in 2004 where he calls for conservatives to change their views on legalization, stating, “We’re not going to find someone running for president who advocates reform of those laws. What is required is a genuine republican groundswell. It is happening, but ever so gradually. Two of every five Americans … believe ‘the government should treat marijuana more or less the same way it treats alcohol: It should regulate it, control it, tax it, and make it illegal only for children.'” In his December 3, 2007 column, shortly after his wife’s death, which he attributed, at least in part, to her smoking, Buckley seemed to advocate banning tobacco use in America.

Buckley died at his home in Stamford, Connecticut, on February 27, 2008 at the age of 82. Initially, it was reported that he was found dead at his desk in his study, a converted garage. “He died with his boots on,” his son Christopher Buckley said, “after a lifetime of riding pretty tall in the saddle.” Subsequently, however, in his 2009 book Losing Mum and Pup: A Memoir, Christopher Buckley admitted that this account was an embellishment on his part: his father had actually been found lying on the floor of his study after suffering a fatal heart attack. At the time of his death, he had been suffering from emphysema and diabetes. In a December 3, 2007, column, Buckley commented on the cause of his emphysema, citing his lifelong habit of smoking tobacco, despite endorsing a legal ban of it. Buckley’s body was buried at the Saint Bernard Cemetery in Sharon, Connecticut, next to his wife Patricia’s.

Buckley later apologized in print for having called Vidal a “queer” in a burst of anger rather than in a clinical context, but also reiterated his distaste for Vidal as an “evangelist for bisexuality”: “The man who in his essays proclaims the normalcy of his affliction, and in his art the desirability of it, is not to be confused with the man who bears his sorrow quietly. The addict is to be pitied and even respected, not the pusher.” The debates are chronicled in the 2015 documentary Best of Enemies.