WASHINGTON — A yearlong State Department study predicted many of the problems that have plagued the American-led occupation of Iraq, according to internal State Department documents and interviews with administration and congressional officials.

Beginning in April 2002, the State Department project assembled more than 200 Iraqi lawyers, engineers, business people and other experts into 17 groups to study topics varying from creating a new justice system to reorganizing the military to restructuring the economy.

Their findings included a much more dire assessment of Iraq's dilapidated electrical and water systems than many Pentagon officials assumed. They warned of a society so brutalized by Saddam Hussein's rule that many Iraqis might react coolly to Americans' notion of quickly rebuilding civil society.

Several officials said that many of the findings in the $5 million study were ignored by Pentagon officials until recently, although the Pentagon said they took the findings into account. The work is now being relied on heavily as occupation forces struggle to bring stability to Iraq.

The group studying transitional justice was eerily prescient in forecasting the widespread looting in the aftermath of the fall of Saddam's government, caused in part by thousands of criminals set free from prison, and recommended force to prevent the chaos.

In a statement issued late Friday, the Defense Department denied that senior military officials had shunned the State Department planning effort.

The broad outlines of the work have been widely known, but new details emerged last week after the State Department sent Congress the project's 13 volumes of reports and supporting documents, which several House and Senate committees had requested weeks ago.

Senior Republican and Democratic lawmakers said the Pentagon, and the Bush administration overall, squandered a chance to anticipate more of the postwar pitfalls by not fully incorporating the State Department information.

But some senior Pentagon officials said that while some of the project's work was well done, much of it was superficial and too academic to be practical.

"It was mostly ignored," said one senior defense official. "Here was the problem: State has good ideas and a feel for the political landscape, but they're bad at implementing anything. Defense, on the other hand, is excellent at logistical stuff, but has blinders when it comes to policy. We needed to blend these two together."

A review of the work shows a wide variety of quality. For example, the transitional justice group met four times and drafted more than 600 pages of proposed reforms. Other groups, however, met only once and produced slim reports or none at all.