By Jerry Lincecum

America’s great glossy magazines were once at the pulsing heart of popular culture. Millions of readers devoured their copies of Life, Look, the Saturday Evening Post, Collier’s, Time, Newsweek, Vogue, Ladies’ Home Journal and more. They were rewarded with provocative stories, stunning photographs, illustrations by popular artists like Norman Rockwell, and appealing ads for sleek new cars and other prizes.

That world has all but disappeared. Most of those plump titles are gone, and the survivors often look like ghosts. It’s a shame because the slick magazines perfected forms of popular journalism, short fiction and fashion coverage that informed and entertained the country.

For decades, Look was the biggest-selling magazine in America. It sold nearly 8 million large-format copies every two weeks, and routinely ran 200 or more pages per issue. But Look perished in the mass-magazine extinction of the late 1960s and early ’70s. Today, it is all but forgotten: None of the nearly 900 issues it published over 34 years has been digitized for posterity.

Look has now been downloaded from magazine heaven by Andrew Yarrow, a reporter and the author of five other books. His lavishly illustrated “Look: How a Highly Influential Magazine Helped Define Mid-Twentieth-Century America” aims not only to rescue the glossy from obscurity but also to burnish its reputation for courageous journalism. In the process, he sketches a compact social history of the country from the Depression to the dawn of the 1970s.

Look was created in 1937 by Gardner (Mike) Cowles Jr., a Midwestern newspaper publisher, just a year after Henry Luce started Life, with which it competed and was compared. Look, Mr. Yarrow claims, was an “iconoclastic—even radical—magazine” full of “powerful photojournalism and “tough-minded optimism.”

To make his case, he has pored over yellowing back issues and microfilm in university and other libraries. Mr. Yarrow is a zealous researcher. It’s hard to imagine that he’s failed to mention any Look article on subjects from Aristotle (philosopher, Greek) to Zappa (rock musician, American), or the work of any photographer from Richard Avedon to the teenage Stanley Kubrick (before he became a movie director).

Mike Cowles was a liberal Republican, and his magazine reflected his values. It was a booster of postwar capitalism and an early crusader for civil-rights progress. The magazine both reflected and encouraged American society’s evolution away from the midcentury model of the nuclear family. In 1971 Look profiled a pioneering gay couple married secretly by their minister, and wrote positively about the lives of single women and divorcees.

Wendell Willkie and later Adlai Stevenson toured world capitals for Look and wrote detailed reports. Sam Castan covered Vietnam and was killed in a skirmish with the Viet Cong while reporting a story about the last thoughts of dying soldiers. Another Look writer conducted a four-hour interview with the young Fidel Castro. A 1970 issue featured pieces by conservative champion William F. Buckley Jr. on “Why We Need a Black President in 1980” and feminist crusader Gloria Steinem on “Why We Need a Woman President in 1976.”

This provocative content often ran beneath covers flaunting Hollywood beauties like Marilyn Monroe, Elizabeth Taylor and Grace Kelly. And the magazine was obsessed with the Kennedys: Between 1959 and ’71, Look ran no fewer than 120 stories about the family. Over the years, it also churned out a remarkable stream of tomorrowland nonsense. In 1953, Look proclaimed that polio, heart disease and cancer were being “conquered.” The media theorist Marshall McLuhan predicted in 1967 that “homosexuality may fade out.”

Look itself faded out in 1971, its circulation and ad revenue ravaged by network television. The internet threat was still decades away. Mr. Yarrow ends his book with a moving elegy: “Look and other mass media,” he writes, “informed people rather than riling them up or scaring them. . . . What ended was not just a great magazine or a type of journalism but a faith that America could be made better.”