Paul Duke, 78, a veteran newsman who for 20 years was the calm and mellow-voiced moderator of "Washington Week," the longest-running news program of the Public Broadcasting Service, died July 18 at his home in the District. He had acute leukemia.

Mr. Duke was already a respected Washington journalist when he took over as host of the program in 1974. He had worked for the Associated Press, the Wall Street Journal and NBC, but at PBS he developed something akin to a cult following as he presided every Friday night over a thoughtful, good-humored discussion of the week's news with four respected journalists.

Mr. Duke set the tone for the print professionals who appeared on the show, then called "Washington Week in Review." They were -- as they are today -- men and women who didn't shout, didn't pontificate and didn't take sides.

"Paul is very serious about journalism," former longtime panelist Charles McDowell told the St. Louis Post-Dispatch on the occasion of Mr. Duke's 1994 retirement. "Like some people care about religion, he cares about journalism. To him, the end of the world is to hear good journalists screaming at each other, playing to the camera."

Mr. Duke often lamented the noisy intrusion of show business into the news business. "I'm a rather old-fashioned journalist in that I believe we lay it out but are not judgmental," he told the Post-Dispatch. "Now a lot of reporters are judgmental. I'm not sure this is a healthy trend."

Mr. Duke's easygoing nature became something of a running joke in Washington. At a 1987 dinner in honor of "Washington Week in Review," then-Senate Minority Leader Robert J. Dole observed: "Paul Duke had a mild case of charisma, but as you can plainly see, he was able to shake it off."

Paul Welden Duke was born in Richmond, where he began publishing his own handwritten neighborhood newspaper at age 13. He was delivering newscasts for a radio station at 16 and had his own 15-minute nightly sports show at 18.

Despite that early experience, he once wrote that, as an English major at the University of Richmond, he had no idea what he would do after graduation. "I had no burning ambitions, no consuming goals," he recalled in an article for the university's journalism department.

Also, his mother looked askance at his becoming a journalist. "Back in the 1940s, journalists had the image of being drunks and bums and ne'er-do-wells," he recalled in a 1994 Washingtonian magazine story written by Ken Adelman.

He took a basic journalism course his senior year simply because he needed the credit. Taught by legendary professor Joe Nettles, the course hooked him. After Mr. Duke graduated in 1947, Nettles helped him get a job covering sports for the Associated Press in Richmond.

A year later, he was writing a weekly "Virginia Sports Reel" column, but reporting on Virginia's civil rights battles began to take more and more of his time. It also won him a promotion to AP's Washington bureau in 1957.

The civility and professionalism that Mr. Duke embodied did not prevent him from being an aggressive reporter. In 1994, Washington Post columnist and occasional "Washington Week" panelist David Broder recalled that at the Wall Street Journal, Mr. Duke was part of a trio of congressional reporters -- along with Alan L. Otten and Robert D. Novak -- that, in Broder's words, "may have been as strong a team as any news organization has ever had on that beat." Mr. Duke covered Congress from 1959 to 1963 as well as the 1960 presidential campaign.

In 1963, he moved to NBC, where he covered Capitol Hill for 10 years. Eager to do live broadcasts about the political news of the day, he switched to public television in 1974. Hosting "Washington Week in Review," seven years old at the time, was part of the deal.

During his tenure, the show's average audience increased from 1.5 million to 4.6 million. It won both an Emmy Award and the Alfred I. duPont-Columbia University Award for outstanding journalistic achievement.

Mr. Duke contributed articles and opinion pieces to numerous publications, including Reporter magazine and The Post, and won an American Film Festival Blue Ribbon for a documentary on Harry Truman's surprise victory over Thomas Dewey in 1948. He also made documentaries about the Berlin Airlift and John F. Kennedy's campaign for the presidency.

The Watergate scandal, he said, was the most emotional story he ever covered, but it wasn't "the greatest story." That, he told Adelman, was a story about Lady Wonder, a horse in Richmond who told fortunes, found missing objects and helped solve love problems.

After his retirement from "Washington Week" in 1994, he lived for nearly two years in London, where he contributed special reports to "Washington Week" on European political matters and news analysis for the BBC. He also provided a weekly "Letter from London" to WETA-FM in Washington.

In 1999, he came back for a short stint as moderator of "Washington Week" after his successor left in a dispute with PBS.

Mr. Duke liked to tell of a letter he received in 1992 from a man accusing "Washington Week" of outrageous bias.

Mr. Duke sent him a one-line response: "Biased which way?"

The viewer came back with his own one-line response: "Biased both ways!"

His marriage to Janet Johnston Duke ended in divorce.

Survivors include his wife of 20 years, Janet Wachter Duke of the District; a son from his first marriage, Paul F. Duke of Los Angeles; a stepdaughter, Amy Rider of Richmond; and a step-grandchild.

Award-winning newsman Paul Duke often lamented the intrusion of show business into his craft.