Laurence Marcus Stern, reporter, editor and author, died of a probable heart attack yesterday while jogging at Martha's Vineyard, Mass.

He was 50 years old.

Stern, an assistant managing editor of The Washington Post, was vacationing with old friends - Ward Just, John Newhouse, Jonathan Randal and Jim Hoagland. They played tennis yesterday and then Stern and Newhouse went jogging.

As they went running, Stern bent over grabbed his ankle and said he had been stung by a bee. He collapsed. Newhouse gave mouth-to-mouth resuscitation. It didn't work. Stern was taken to Martha's Vineyard Hospital, but he was dead when he arrived.

Stern had been a writer and editor for The Post since 1952, winning awards and cutting a wide swath in both American and international journalism.

Benjamin Bradlee, executive editor of The Post, issued this statement:

"His paper and his friends will be a long time getting over the loss of Larry Stern. He was a world class journalist. He wrote like a dream, with grace and precision. His commitment to excellence, to his staff, to his friends and to The Washington Post will be an example for all of us."

Stern was a newspaper child. His father, Augustus (Gus) Stern, worked in Washington for many years as a copy editor for various local newspapers, the last being The Post.

Larry Stern followed his father. He served in the Army after World War II and got a taste of journalism working for the military newspaper, The Stars and Stripes.

Thereafter, he was educated at the University of Missouri and the New School for Social Research in New York. He worked briefly for the former United States Information Agency and joined The Post in 1952 as a reporter on the metropolitan staff.

He took off in that business like a great running back - national reporter, national editor, foreign correspondent, editor of Style, and, finally, assistant managing editor for national news.

He wrote a much-admired book, "The Wrong Horse," which dealt with the tragedy of Cyprus, and he contributed to several other books. He wrote magazine articles and even as an editor responsible for a large staff, constantly looked for opportunities to write. He found them frequently.

Stern had another, informal, function at The Post. He was a bridge between this country and journalists from around the world. They sought him out always - Vietnamese, Englishmen, Frenchmen, Turks, Greeks. That was a tribute to his international understanding and to his personality.

His career had an interesting progression. He won many awards writing about politics and corruption in the Washington metropolitan area. He moved then into the national arena and was singularly successful in dealing with the social and political issues of American life. But in the last years of his life, it was really international questions that absorbed his interest and energies.

He became early in the '70s, The Post's first "Dulles Airport correspondent," available day or night to fly anywhere in the world for the big story. The job took him to Vietnam, Cambodia and Laos for almost two years, where he observed in combat the collapse of the American effort. He covered the war in Cyprus, reported from the Middle East, from Italy, from London, from Paris, from Greece.

British journalists intrigued him most of all. Among them, his friends were legion. He admired, especially, the Insight team of the Sunday Times of London and set up his own Insight unit at The Post in the late 1960s. There was an "Insight" project at the top of his list when he died yesterday.

Stern, one of his subordinate editors said yesterday, was "something of an enigma. It became something of a newsroom conceit, after Larry had had a dialogue with a colleague, to say, "I don't know what he said. I don't speak Zen." This never detracted from the fact that Larry knew exactly what a news article should say and how it should be said."

One reporter on the national staff of The Post who had worked for Stern for several years volunteered this observation:

"When Larry Stern was working on the national staff as a reporter, you could feel the whole atmosphere change. He was a reporter who made a difference - not only because of what he contributed to the paper under his own byline but because of the standard he set for everyone around him. Other reporters found themselves writing with more life and crispness because he was there doing it - pushing the rest of us."

There was a certain disorganization about his life. He made too many luncheon dates on the same day. He loved many women. Budgets never enthralled him. His checkbook was not often tidy. It was a legend at The Post that Stern mumbled ambiguous instructions, might or might not show up for this meeting or that and and probably would forget where he had parked his car.

But when it came to the job, to getting things done, he had no superior. He could produce instant and rather profound work - books, newspaper series, essays.

The honors his own profession gave him were impressive - the George Polk Memorial Award, the American Political Science Association Award, the Headliners Club Award, the Newspaper Guild Award, the fellowship of the Carnegie Endowment for International Peace. He was proud, for reasons his friends never knew, of having been one of the inventors of a game called "Influence," a political version of Monopoly.

His children, Catherine O'Brien, Marcus, Gunther and Christopher, shared that pride.

One of Stern's friends responded to his death with a fragment from a poem:

Oh, I have slipped the surly bonds of earth,

And danced the skies on laughter's silvered wings.

Sunward, I've climbed and joined the tumbling mirth

Of sunsplit clouds, and done a hundred things you've not dreamed of....

And while with silent, lifting mind I've trod,

The high untrespassed sanctity of space,

Put out my hand and touched the face of God. CAPTION: Picture, Laurence Stern: "He was a reporter who made a difference."