Michael Whitney Straight, author, painter, former deputy chairman of the National Endowment for the Arts, former editor and publisher of the liberal publication The New Republic, former State Department economist, former reluctant Soviet agent during the Cold War and a longtime Chilmark seasonal resident, died Sunday at his home in Chicago after a brief illness. He was 87.

On the Vineyard, it is for his love of and ability at tennis and sailboat racing, his fascination with the natural world around him, his vigorous support of conservation causes and for his friendship that he will be remembered.

He was a founder and former president of the Vineyard Conservation Society and was on the board of overseers of the Vineyard Open Land Foundation. He was a lifelong supporter of Felix Neck Wildlife Sanctuary and was an early and important contributor last summer to the purchase of a conservation restriction on the Ryerson land on Chilmark's Chalker's Point Peninsula by the Sheriff's Meadow Foundation. He was a supporter of the Polly Hill Arboretum and The Yard. In the 1960s, before the purchase of the Vineyard Gazette by the late James B. and Sally Fulton Reston, his interest in preserving the Island led him to consider buying the Gazette himself as an editorial vehicle for such preservation.

Although his earliest childhood summers were spent in Quisset rather than the Vineyard, his paternal grandfather, Henry H. Straight, had come to the Vineyard in 1883 to teach physical science at the Martha's Vineyard Summer Institute on the East Chop Highlands. Later, his grandfather had helped direct a Summer School of Natural Sciences on Penikese Island. This resulted eventually in the establishment of the Marine Biological Laboratory at Woods Hole and made Quisset the family's summer home. But there would be occasional summer outings to Vineyard Haven to the Hines Point home of his aunt, Hazel Straight Sanborn, and her husband, James. It was not until much later, after his education and first marriage, that he seriously discovered the Vineyard.

Michael Straight was born in Southhampton, N.Y., Sept. 1, 1916, the third child of Willard D. Straight, an investment banker, and Dorothy Payne Whitney Straight, daughter of William C. Whitney, financier and Secretary of the Navy under President Grover Cleveland. His siblings were Whitney, who became a racing car driver and the head of the British Overseas Airways Corporation, and the actress Beatrice Straight. In 1914, his parents started the magazine, The New Republic.

Willard Straight died in Paris in 1918 while serving on the U.S. delegation to the Versailles Peace Conference. (Michael, his West Tisbury friend Gerald DeBlois recalled, insisted he remembered seeing paraders celebrating the armistice on Fifth avenue, watching from his family's apartment window, though he was little more than two.)

In 1925, Dorothy Straight married Leonard K. Elmhurst and moved, with her children, to England. There, she and her husband began an experimental community and school called Dartington Hall. Young Michael attended the London School of Economics and Cambridge University. There, he became a pupil and friend of the economist John Maynard Keynes and a fellow member, with Keynes, of the Apostles, a Cambridge secret society. Along with Keynes, fellow members in Michael Straight's day were Guy Burgess and Anthony Blunt, both of whom would later be known for their espionage activities on behalf of the Soviet Union. And, Michael Straight acknowledged in his 1983 memoir, After Long Silence, at Cambridge he was recruited into the Communist movement by Blunt and Burgess. He was, he wrote, distraught and in mourning after a close friend had been killed fighting for the left against Franco in the Spanish Civil War. When Blunt and Burgess told him he would be working for the same good cause for which his friend had lost his life, he agreed that he would work secretly for them from Washington.

Before returning to the United States in 1937, he joined his racing car aficionado brother, Whitney, in flying to South Africa, where they finished first and third in the first South African Grand Prix. Back in America, he first worked as a volunteer in the State Department and then joined a team of ghost writers for President Franklin Delano Roosevelt and his cabinet.

It was in this Washington period - still dreaming of a better world - that he began supplying economic reports he had done for the State and Interior Departments to the Soviets. But he always played down their political significance, he wrote in his memoir.

In the 1940s, he left government service to become Washington editor of The New Republic, which his mother still owned. Then in 1941, he became its editor, shifting its isolationist political viewpoint to reflect his own anti-Fascist, anti-Hitler sentiments. In a series of articles and editorials, he called for a massive defense effort, full support for Great Britain and a declaration of war against Germany. He wrote a book, Make This the Last War, in 13 weeks, and, in 1942, he joined the Army Air Corps and learned to fly B-17s. Stationed in the Midwest, he was assigned to teach French airmen to fly.

Meanwhile, in 1939, he had married Belinda Crompton, a child psychiatrist, and they had begun their family.

In 1945, he returned to The New Republic as publisher and recruited the controversial New Deal philosopher and spokesman and former vice president, Henry Wallace, to be its editor. Two years later, after Mr. Wallace departed, Mr. Straight shifted the editorial policy to oppose Stalinism and support the Marshall Plan.

Although, politically, he was now anti-Stalin, when Sen. Joseph R. McCarthy began his anti-Communist witch hunt, Mr. Straight took strong issue with the senator wherever he could.

In 1953, Mr. Straight had sold his magazine to Gilbert Harrison of Chilmark and Washington, D.C., and no longer had it as a podium, but in a 1954 speech at Stevens Memorial Chapel in Vineyard Haven, he asked how the nation could possibly have fallen into the McCarthy grip. He also, that year, wrote a book, Trial by Television, critical of both McCarthy and Communism.

In the 1950s, Mr. Straight became the national chairman of the American Veterans Committee and the founder-president of Amnesty International. He also wrote two novels, Carrington and A Very Small Remnant.

In 1963, he was asked by President Kennedy to become chairman of the newly created National Endowment for the Arts. It was because of this invitation that he felt obliged to tell the full story to the FBI of his earlier links with the Communist party and his espionage activities. They, in turn, passed on his intelligence information to British counter-intelligence. His story, backed by an offer he made to confront Blunt in a British court, led to Blunt's confession. By this time, Blunt was a highly placed, much admired art historian.

In 1969, Mr. Straight was chosen by President Nixon to be deputy chairman of the National Endowment for the Arts under Nancy Hanks. Their partnership led to a twelvefold increase in government spending on the arts between 1970 and 1979.

Mr. Straight began regular Vineyard visits in the 1950s, renting in Blacksmith Valley and at Abel's Hill before, in 1961, building an 11-room house down Chalker's Lane on Quitsa Pond. He had long known and admired American Civil Liberties founder Roger Baldwin, who had a Chilmark summer home, and his presence on the Island made it particularly alluring.

Mr. Straight was devoted both to the land around his house, where he planted trees and shrubs and indefatigably cut wood, and to the waters below it. He and his daughter Dorothy this past fall, spent hours trying to identify autumn clematis that they had seen and admired flowering at Clarissa Allen's farm.

He became the commodore of the Menemsha Pond Racers, setting out the course for the twice-weekly races and manning the 22-foot lapstrake committee boat that he named Dorothy after his youngest daughter. It appears in a Thomas Hart Benton painting of a race at Herring Creek. When he finally turned over the running of the races to Arthur Railton in the 1970s, he began racing in earnest himself - first in a Sailfish, then in a Laser - and he was frequently a winner.

Journalist that he was, he encouraged and assisted his children in their publication of the Green-Spring Menemsha Gazette, filled with the youngsters' interviews, drawings and local news.

In 1964, when five West Tisbury women went south to join civil rights protests and were arrested in North Carolina, he hosted them at brunch when they headed home.

Tall and vigorous, whenever he was here, he played tennis the first thing each morning either at his friend Gil Harrison's court, which Mr. Straight maintained for the players himself, or at Gerald DeBlois's West Tisbury court. Among regular fellow players were Chilmarkers Stan Hart and Don Davis. He continued well into his 80s to take lessons each spring from tennis pro Matt Mirchell, who said of his passing: "I'm sending doves today into the great blue sky. You will be missed, my friend."

An inveterate reader and devoted to art, he had begun painting early in life and returned to it later, painting in Mexico, in the south of France and on the Island. Among his Island paintings were portraits of his friends the late Craig Kingsbury and the late Stan Murphy.

He frequently attended recitals at The Yard and was a staunch supporter of it and of the Chilmark Public Library. A play he wrote, Caravaggio, was performed by, among others, the Vineyard Players. He was often called upon to speak by local organizations and readily accepted whether it was at the First Congregational Church or the Martha's Vineyard Garden Club.

He was endlessly fascinated by his natural surroundings and for more than a dozen years the same seagull, Greedy, would return each summer to the Straight property where it was always Mr. Straight it sought out by tapping on the glass doors. He had Gus Ben David erect an osprey pole for him and zealously recorded osprey births and comings and goings each year. He also had an owl's roost erected for him. To keep his grass cropped, he "rented" three sheep each summer from the late Ann Hopkins.

Mr. Straight was divorced from his first wife in 1969, and in 1974 married Nina Gore Auchincloss Steers. They subsequently divorced and in 1998 he married Katherine Gould, a child psychotherapist, who survives him.

He is survived also by five children, David Willard Straight of Knoxville, Tenn., Michael Willard Straight of Rockville, Md., Susan Romilly Straight of Trumansburg, N.Y., Dina Straight Krosnick, a New York city public schoolteacher, and Dorothy Elmhirst Straight of Byfield; stepsons Emile and Matteo Levisetti and Burr Steers, and grandchildren Noah and Willow Rindos and Gwendolyn and Joshua Krosnick. A private memorial service will be held on the Vineyard this summer. Donations in his memory may be made to The Yard, the Polly Hill Arboretum or the Felix Neck Wildlife Trust.