In a memoir being published this month, Sen. Edward M. Kennedy called his behavior after the 1969 car accident that killed Mary Jo Kopechne “;inexcusable”; and said the events may have shortened the life of his ailing father, Joseph P. Kennedy.

In that book, “;True Compass,”; Kennedy said he was dazed, afraid and panicked in the minutes and hours after he drove off a bridge on Chappaquiddick Island with Kopechne as his passenger.

He admitted that he had “;made terrible decisions”; but said that he had hardly known Kopechne, a young woman who had been an aide to his late brother Robert, and that he had had no romantic relationship with her.

The account by Kennedy, who died on Aug. 25 at age 77, adds little to what is known about the accident and its aftermath but recounts how they weighed on him and his family. The book does not shy from the accident, or from some other less savory aspects of the senator's life, including a notorious 1991 drinking episode in Palm Beach, Fla., or the years of heavy drinking and women-chasing that followed his 1982 divorce from his wife, Joan.

But it also offers rich detail on his relationships with his father, siblings and children that round out a portrait of a man who lived the most public of lives and yet remained something of a mystery. Among other things, it says that in 1984 he decided against seeking the presidency after hearing the emotional objections of his children, who, it says, feared for his life.

A copy of the 532-page memoir, scheduled for sale Sept. 14, was obtained by The New York Times.

In it, Kennedy also said he had always accepted the finding of a presidential commission that a sole gunman, Lee Harvey Oswald, was responsible for President John F. Kennedy's assassination. Robert F. Kennedy grieved so deeply over the killing of the president that family members feared for his emotional health, Kennedy wrote, saying that it “;veered close to being a tragedy within a tragedy.”;

Kennedy's book provides new details about life in America's famous political family and covers the remarkable career that was celebrated in memorials last week before his burial near John and Robert Kennedy in Arlington National Cemetery. It provides his personal account of being stricken by the brain cancer that took his life and his decision to battle the disease as aggressively as he could. And it deals openly and regretfully with “;self-destructive drinking,”; especially after his brother Robert's death.

Kennedy said that his father had encouraged intensive competition among his children, especially his sons, which fed his recurrent feelings of inadequacy after the death of his three brothers, all of them older.

“;Competition, of course, is the route to achievement in America,”; Kennedy wrote. “;As I think back to my three brothers, and about what they had accomplished before I was even out of my childhood, it sometimes has occurred to me that my entire life has been a constant state of catching up.”;

The book, published by Twelve, a division of the Hachette book group, was originally scheduled to be published in 2010 to coincide with the 50th anniversary of the election of President Kennedy but was moved up because of the senator's illness. Much of the book, written with a collaborator, Ron Powers, was based on notes taken by Kennedy over 50 years as well as hours of recordings for an oral history project at the University of Virginia.

The memoir also suggested that President Kennedy had grown uneasy about events in Vietnam and was increasingly convinced that the conflict could not be resolved militarily. It said the president's “;antenna”; was up, and surmised that he was “;on his way to finding that way out,”; though “;he just never got the chance.”; Kennedy wrote of a secret meeting in the spring of 1967 between President Lyndon B. Johnson and Robert Kennedy, whose increasingly outspoken criticism of the war in Southeast Asia was becoming a political threat to Johnson. According to the book, Robert Kennedy proposed that Johnson give him authority to personally negotiate a peace treaty in Vietnam. This implicitly would have kept Robert from running for the 1968 Democratic presidential nomination, a prospect that deeply worried Johnson.

“;If the president had accepted his offer,”; the book said, “;Bobby certainly would have been too immersed in the peace process to become involved in a presidential primary.”;

But Johnson could not take the offer at face value, concerned that Kennedy had ulterior motives, the senator wrote.

In raw and often intimate terms, Kennedy wrote of the despair he experienced after Robert's assassination in 1968. It was at first impossible for him to return to the Senate. And even when he managed to, he could not focus on his work. He spent days on at the ocean, taking long sails from the family compound in Hyannis Port, Mass.

“;Sometimes I sailed for long distances,”; he wrote. “;Sometimes I sailed to Maine.”;

He described drinking to excess during that period and driving his first wife, Joan, “;deeper into her anguish.”; He drove himself and his staff hard. “;I tried to stay ahead of the darkness,”; he wrote.

The shooting of his brothers traumatized him in ways both existential and mundane, Kennedy noted. He would flinch at loud, sudden noises like the explosion of firecrackers, or hit the deck whenever a car backfired.

Kennedy also revealed that he had written a letter to the Los Angeles district attorney asking that he not seek the death penalty for Robert Kennedy's assassin, Sirhan Sirhan. (The judge, Herbert V. Walker, disregarded the letter, Kennedy said, though Sirhan's life would be spared by the California Supreme Court.)

The book opens with an account of Kennedy's falling ill and then, in May of last year, receiving a diagnosis of a lethal brain tumor. Doctors said he had just a few months to live, Kennedy wrote, but he refused to believe the grim prognosis, because he had been raised not to give up. His son Teddy Jr. had survived a supposedly fatal cancer in his leg, and his daughter, Kara, had beaten lung cancer, against long odds.

“;And I believe that approaching adversity with a positive attitude at least gives you a chance for success,”; he said. “;Approaching it with a defeatist attitude predestines the outcome: defeat. And a defeatist's attitude is just not in my DNA.”;

Kennedy expressed regret over the 1991 episode in Palm Beach, when he went drinking with his son Patrick and his nephew, William K. Smith, who would be charged with rape that allegedly occurred that night. (Smith was later acquitted.)

Those events hobbled him later that year when Clarence Thomas was nominated for a seat on the Supreme Court. Kennedy strongly opposed the nomination, but, he wrote, he could not speak out as forcefully as he would have liked.

“;I also understood another hard truth: with all the background noise about Palm Beach and my bachelor lifestyle, I would have been the wrong person”; to raise questions about Thomas' alleged sexual harassment of Anita F. Hill.

But even as he offered apologies for the darker moments of his life, he raged against the portrait of him in some tabloids, magazines and books. He described some of those accounts as “;totally false, bizarre and evil theories.”;

Of his indulgences, Kennedy wrote: “;I have enjoyed the company of women. I have enjoyed a stiff drink or two or three, and I've relished the smooth taste of a good wine. At times, I've enjoyed these pleasures too much. I've heard the tales about my exploits as a hell-raiser—some accurate, some with a wisp of truth to them and some so outrageous that I can't imagine how anyone could really believe them.”;

Kennedy wrote about his views of various presidents, sometimes affectionately, sometimes harshly. Some of his most critical words are directed against Jimmy Carter.

He said that while they had found common cause on a few issues, their relationship had broken down over health care. He accused Carter of timidity that doomed any chance of meaningful health insurance reform and said the president had been virtually impossible to talk to.

“;Clearly President Carter was a difficult man to convince—of anything,”; Kennedy wrote. “;One reason for this was that he did not really listen.”;

Kennedy also complained that White House meetings had been barely tolerable, in part because no liquor was ever served during Carter's term. “;He wanted no luxuries nor any sign of worldly living,”; Kennedy wrote.

While Kennedy had little patience for the president's piety and punctiliousness, he found the disengagement of Carter's successor, Ronald Reagan, at times oddly charming, though at other times frustrating. The senator said it had been difficult to get Reagan to focus on policy matters. He described a meeting with him that he and other senators had sought to press for shoe and textile import limits.

The senators were told that they would have just 30 minutes with the president. Reagan began the meeting, the book said, commenting on Kennedy's shoes—asking if they were Bostonians—and then talking for 20 minutes about shoes and his experience selling shoes for his father. “;Several of us began conspicuously to glance at our watches.”; But to no avail. “;And it was over!”; he said. “;No one got a word in about shoe or textile quota legislation.”;

Kennedy said he had been disappointed by President Bill Clinton's inability to enact comprehensive health care legislation, but he did not blame Clinton or his wife, Hillary Rodham Clinton, who helped write the administration's proposal.

He also said he called Clinton immediately after the president appeared on television to confess his affair with Monica F. Lewinsky, reassuring him that he would stand by him during that difficult period.

In the midst of recounting that anecdote, Kennedy took a break to offer his views on the scrutinizing of the private lives of public officials, something with which he clearly was quite familiar. Kennedy said he had no quarrel with such inquiries.

“;But do I think it tells the whole story of character? No I truly do not,”; he wrote. Men and women, he said, are more complicated than that. “;Some people make mistakes and try to learn from them and do better. Our sins don't define the whole picture of who we are.”;