Penn Kimball, the journalist, author and mentor to a generation of fledgling reporters as a professor for 27 years at Columbia University’s Graduate School of Journalism, died Friday, Nov. 8, at a Chevy Chase, Md., nursing home. He had a summer home in Chilmark for more than 50 years, and lived in Vineyard Haven and Oak Bluffs year-round from 1994 to 2009. He was 98 years old.

A defiantly proud yellow-dog Democrat, Mr. Kimball sued the federal government for $10 million after he discovered that he and his late wife, Janet, had been declared national security risks in the 1950s. (He eventually won an apology of sorts from the government, but no money.) He told the story in his book The File, which became a BBC and later a Frontline documentary. “I refused to believe that you can’t fight the government and bring them to account,” he said after it had backed down and admitted it had no evidence that he or his wife had ever been disloyal.

A lifelong liberal — he once took his infant daughter Lisa into a Connecticut polling booth, pointed to the Republican lever, and said, “Red hot! Don’t touch!” — Mr. Kimball was a political consultant to two Democratic governors, Chester Bowles of Connecticut and Averell Harriman of New York, as well as to Connecticut Senator William Benton, working with the senator in his pioneering denunciation of Senator Joe McCarthy. Mr. Kimball also worked in a variety of media, from newspapers and magazines to live television, before becoming a Columbia professor.

Penn Townsend Kimball II was born in New Britain, Conn., on Oct. 12, 1915, the son of Arthur Gooch Kimball and Effie Smallen Kimball. An Eagle Scout, he was educated at Lawrenceville and Princeton, where he was editor in chief of The Princetonian. He left for Balliol College, Oxford, as a Rhodes Scholar in 1937, where he earned a master’s degree in politics and economics. Two years later he was planning to continue his studies in Grenoble, France, but returned home on what turned out to be the last passenger ship to sail before the outbreak of World War II. He began his career as a writer and editor at what was then called U.S. News, in Washington, D.C., and then for PM, the experimental leftist newspaper in New York city. He joined the Marines after Pearl Harbor and served for four years in the Pacific, retiring as a captain.

Working as a writer for Time magazine, he met and married Janet Fraser, who was a researcher there, in 1947. They had a daughter, Lisa, and lived for many years in Westport, Conn., spending summers in a hilltop cottage originally owned by Lou King in Chilmark until Janet’s death in 1982. Mr. Kimball also worked as a writer and editor for Collier’s Magazine, The New York Times, The New Republic, and he was an election consultant for CBS and a producer/writer on the experimental, live TV program Omnibus. It was his idea to have Leonard Bernstein explain music to children on an Omnibus program, which later led to the conductor’s acclaimed series of televised children’s concerts.

Mr. Kimball was also the author of The Disconnected, Bobby Kennedy and the New Politics, Keep Hope Alive: Super Tuesday and Jesse Jackson’s 1988 Campaign for the Presidency, and Downsizing the News: Network Cutbacks in the Nation’s Capital.

He joined the Columbia journalism school faculty in 1958, where his occasionally cantankerous nature was a thorn in the side of many of the school’s deans. One was quoted in print as saying that Mr. Kimball was a “sour apple” he had to tolerate because he was tenured. Mr. Kimball’s students promptly ordered up a T-shirt with the words “sour apple” on the front and “tenured” on the back — which he wore to the next faculty meeting. He was famous for telling students “go there” as he sent them to the far corners of New York city to practice shoe-leather reporting. “There’s no such thing as a boring subject,” he was fond of saying. “Only boring reporters.”

In the 1970s he worked with renowned urban renewal expert Edward Logue on a several projects, including one to revitalize the South Bronx, and authored a report, Areas of Strength, Areas of Opportunity, based on his belief in building on existing community assets rather than razing everything to start over, as was a common practice at the time.

He married Julie Ellis, a journalist, in 1985, and after retiring from teaching, earned a Ph.D. from Columbia in political science, was a fellow at the Woodrow Wilson Center in Washington, D.C, wrote two more books, and traveled to China to adopt an 8-year-old daughter whom he and his wife named Laura. She is a 2008 graduate of Martha’s Vineyard Regional High School. They moved to the Island in 1994, living year-round in Vineyard Haven, and later in Oak Bluffs, before returning to Washington in 2009.

Besides his wife and two daughters, both of Washington, D.C., he is survived by two nieces and a nephew.

A memorial service will be held on Monday, Dec. 9, at the National Press Club in Washington, D.C. There will also be a service next summer on Martha’s Vineyard.