Pell was first elected to the Senate in 1960. The skinny son of a New York congressman, Pell spoke with an aristocratic tone but was an unabashed liberal who spent his political career championing causes to help the less fortunate.
He disclosed he had Parkinson's in 1995 and left office in January 1997 after his sixth term.
Members of Rhode Island's all-Democratic congressional delegation lauded Pell's legacy.
"Senator Pell was a remarkable statesman and legislator who worked tirelessly to promote peace and expand opportunity through education," Sen. Jack Reed said in a written statement.
"We will all miss him deeply, and long benefit from the works of his farseeing soul," Sen. Sheldon Whitehouse said. And Rep. Jim Langevin called Pell a "gentleman and champion for those who needed their voices heard."
When asked his greatest achievement, Pell always was quick to answer, "Pell Grants."
He sponsored legislation creating the Basic Educational Opportunity Grants, which passed in 1972 and provided direct aid to college students. The awards were renamed "Pell Grants" in 1980.
By the time Pell retired, they had aided more than 54 million low- and middle-income Americans.
"He believed strongly that a good education could open infinite doors of opportunity, and he has transformed the lives of millions of young people who have been able to go to college because of the grant that rightly bears his name," said Sen. Edward Kennedy, D-Mass.
Thomas Hughes, Pell's chief of staff from 1975 until his retirement, said Pell believed financial aid should be given directly to students rather than distributed by colleges and universities.
"He always had this view that the federal government should help young people be able to have an education beyond high school," Hughes said.
Quiet, thoughtful and polite to a fault, Pell seemed out of place in an era of in-your-face, made-for-television politicians. A multimillionaire, he often wore old, ill-fitting suits and sometimes jogged in a tweed coat.
Though criticized by some for his fascination with UFOs and extra sensory perception, he was best remembered for his devotion to education, maritime and foreign affairs issues.
Pell also shared a strong interest in the arts, and was chief Senate sponsor of a 1965 law establishing the National Endowment for the Arts and the National Endowment for the Humanities.
Pell was well-liked among peers from both political parties, who respected his non-confrontational style. "I believe in letting the other fellow have my way" was a favorite refrain Pell used to refer to his negotiating skills.
Born in 1918, Pell came from a political family and was a descendant of early New York landowners who lived among the old-money families in Newport. Five family members served in the House or Senate, including great-great-granduncle George M. Dallas, who was a senator from Pennsylvania in the 1830s and vice president under President James K. Polk in the 1840s. His father, Herbert Claiborne Pell, was a one-term representative from New York.
Pell graduated from Princeton in 1940, and served in the Coast Guard during World War II. He remained in the Coast Guard Reserve until retiring as a captain in 1978.
He participated in the 1945 San Francisco conference that drafted the United Nations charter and was a staunch defender of the institution throughout his life.
He served in the foreign service for seven years, holding diplomatic posts in Czechoslovakia and Italy, then returned to Rhode Island in the 1950s. He was elected to the Senate in 1960 after defeating two former governors in the Democratic primary.
Despite his peculiarities, he became the most formidable political force in Rhode Island. In his six statewide elections, he received an average 64 percent of the votes.
"I attribute (my popularity) to one reason, and that is I have never critically mentioned my adversary," Pell would say.
The late Republican Sen. John Chafee of Rhode Island once said Pell's popularity was due to the state's overwhelmingly Democratic leanings and Pell's honesty and integrity. Voters embraced Pell's quirkiness and, to a certain extent, his distance from common people.
A story from Pell's 1972 Senate campaign was a favorite in Rhode Island and was told often to illustrate his isolation from the average Joe.
Pell was campaigning in Providence when it began raining. Pell, who had a formal evening engagement, had forgotten his galoshes. An aide was dispatched and returned with a pair.
In his very formal manner of speech, Pell asked the aide, "To whom am I indebted for these fine rubbers?"
"I got them at Thom McAn, senator," the aide answered, referring to the budget shoe store chain.
"Well, do tell Mr. McAn that I am much obliged to him," Pell said.
A dove who vigorously opposed the Vietnam War, Pell in 1987 became chairman of the Foreign Relations Committee. He was considered a weak chairman, and he lost the job to Sen. Jesse Helms of North Carolina when Republicans gained a majority in 1994.
Pell considered retiring in 1990, but was persuaded by party leaders to run. He easily defeated then-U.S. Rep. Claudine Schneider despite making a monumental gaffe during a televised debate in which he was asked to identify a piece of recent legislation he had sponsored to help Rhode Islanders.
"I couldn't give you a specific answer," Pell said. "My memory's not as good as it should be."
Pell was diagnosed with Parkinson's disease in December 1994 and disclosed the condition the following spring. He insisted the disease had nothing to do with his retirement.
"There is a natural time for all life's adventures to come to an end and this period of 36 years would seem to me about the right time for my service in the Senate to end," he said in September 1995.
When attending a July 2006 ceremony in his honor in Newport, Pell did not talk, letting his wife, Nuala, speak on his behalf.
He and his wife, who married in 1944, had four children. Their daughter Julia died of lung cancer in 2006 at age 52.