Even before they could digest the book-length report by the commission investigating the Sept. 11, 2001, attacks, relatives of the victims began pressing Congress and President Bush to implement its raft of recommendations.

As they emerged from a pair of briefings yesterday -- many clutching the 567-page bound report -- survivors of the attacks and relatives of the dead praised the commission as having done thorough work under tight deadlines and intense political pressure. And like the commissioners themselves, the families declared that July 22, 2004, was not an ending but yet another beginning in their effort to ensure that no other American endures a similar loss of life.

"My worst nightmare is this report will be collecting dust on a shelf somewhere," said Robin K. Wiener, a Washington lobbyist whose brother Jeff died in the World Trade Center. "We've all been warned: Something is going to happen. It is absolutely critical these recommendations be implemented as quickly as possible."

Release of the report culminated a 20-month investigation that might not have taken place were it not for the persistence and outspokenness of the Sept. 11 relatives, who call themselves the Family Steering Committee. Their lobbying helped persuade the White House to form the commission, and at several critical junctures they were credited with pushing administration officials to testify or Congress to allocate more money.

In its unanimous report, the panel of five Democrats and five Republicans detailed years of systemic governmental failures and called for extensive changes in how the United States collects, evaluates and acts on intelligence. Family members endorsed the commission's proposal to create a Cabinet-level intelligence post and voiced anger at comments by some Republican leaders who disagreed.

"The administration would be very negligent if they don't go along with the suggestions," said Matt Sellitto, whose 23-year-old son, Matthew, worked at the World Trade Center. "If we let our Congress not implement these suggestions, we are all at fault."

About 30 relatives received a private 45-minute session with commission Chairman Thomas H. Kean and Vice Chairman Lee H. Hamilton, and then attended a news briefing, sometimes interrupting with applause. When they came out into the hot midday sun, they reported feelings of exhaustion, relief, frustration and determination.

"I am a little tired," Abraham Scott said. But even after working late Wednesday at the Department of Veterans Affairs, he said, he would not have missed yesterday's session. His wife of 23 years, Janice M. Scott, 46, had received a promotion shortly before she perished in the Pentagon.

One of the few sources of frustration with the commission's report was the absence of a conclusion on whether the attacks might have been prevented.

"When you look at the litany of missed opportunities, it's pretty clear it could have been prevented," said Beverly Eckert of New Jersey, whose husband, Sean Rooney, died in the World Trade Center.

For Donn Marshall, more painful than the report were the video images broadcast Wednesday night of several hijackers passing through metal detectors at Dulles International Airport.

"Watching the people who killed my wife and knowing there is nothing I can do to them is frustrating," he said in a telephone interview from West Virginia. After his wife, Shelley, died in the Pentagon, he moved their two children out of concern that Washington was still a target.

For many, the investigation was an education in the arcane mores of bureaucratic Washington. Yet in the process, they grew into some of the most sophisticated -- and successful -- lobbyists in the Capitol.

When they began their quest for answers, Lorie Van Auken recalled, they had trouble keeping the House and Senate straight. Yesterday, she had tough talk for House Speaker J. Dennis Hastert (R-Ill.), who said Congress is unlikely to tackle the recommendations this year.

"That's a terrible shame," said Van Auken, 49. "We had a lot of hearings; the commissioners spoke to a lot of experts. There is no excuse to not get started right away."

Hastert had annoyed the family members once before, when he balked at extending the commission's term. They raised such a protest that he relented and his spokesman credited them.

April Gallop, 33, brought her son, Elisha, 3, to the briefing. They narrowly escaped the Pentagon, though she sustained spinal and brain injuries that forced her to retire. "Talk is cheap," she said. "We need to see tangible evidence progress is being made."

Sept. 11 widows Kristen Breitweiser, left, and Lorie Van Auken look at the commission report during the final hearing.