Kenneth W. Rendell’s “Safeguarding History: Trailblazing Adventures Inside the Worlds of Collecting and Forging History” straddles several genres: While mainly a chatty, easygoing autobiography, it’s also a business history, a family memoir and a highly anecdotal introduction to an arcane field. Above all, though, it’s what we in the reviewing trade call “a fun read.”

Born in 1943 into a hard-working family in the Boston area, Rendell started collecting and selling coins at age 12, and — through a combination of industriousness, careful calculation and a willingness to follow his instincts — rose to become the leading American dealer in historical documents, an expert on the detection of forgery and a friend to distinguished people in many fields. This new book, for instance, carries a cover blurb by filmmaker Ken Burns, praise for Rendell from actor Tom Hanks and a preface by Pulitzer Prize-winning historian Doris Kearns Goodwin.

As he makes plain again and again, Rendell subscribes to the American Dream, the conviction that with determination, know-how and grit, anyone can become anything. “When I look back at myself at 12 years old,” he writes in recalling his youthful entry into buying and selling early American coins, “I realize that I had begun what became a lifelong process of always looking at what value I could add to a business situation. What would make me successful, how did I improve a process, how could I offer more service, why should I be successful?” That said, this old-fashioned approach to business success — find a need and fill it — doesn’t preclude a distinctly Thoreau-like approach to life in general: “The greatest adventure,” Rendell insists, “is in exploring yourself, discovering who you really are, learning what is important to you, and finding out what you really want and enjoy in life and — equally important — what you don’t want.” In his own case, Rendell recognizes that his family and time spent in the natural world are for him the great essentials for happiness.

Rendell grew up in a rough-and-tumble area of Somerville, Mass. “I played ball with neighborhood kids and soon got to know the prison sentences for just about every crime. Everyone’s father seemed to be in prison, had just gotten out of prison, or was awaiting trial. The kids I knew all aspired to do better than their fathers — they weren’t going to get caught as often.” One day, though, a customer at the family’s down-at-the-heels drugstore paid for his purchase with what turned out to be an 1806 half-dollar. Rendell’s mother gave the oddity to her son, and the 12-year-old visited three coin dealers before selling it for $3.50. All the way home on the bus, he recalls, he said to himself, “Wow, this is the way to make a lot of money.” By age 14, Rendell was bringing out monthly two-page catalogues devoted to pre-revolutionary copper coins. As for that original 1806 half-dollar? He bought it back as soon as he could, and the coin “has sat on my desk ever since that day in 1954.”

At age 17, the youthful coin dealer sold his business to focus on a new passion — historical documents. Despite the emotional toll of his father’s sudden death the following year, Rendell kept at this new field while taking nightschool courses in accounting and office management. During the following decade, he drew on what he learned from those classes, his own collecting savvy and, perhaps most important, the kind of social skills that Dale Carnegie would envy as he began to buy and sell presidential autographs, significant letters and unusual paper ephemera.

By the 1970s, Rendell was traveling to Europe, acquiring handwritten material by, among others, Michelangelo, Henry VIII, Sigmund Freud, Arthur Sullivan (of Gilbert and Sullivan fame), Paul Gauguin and Pablo Picasso. By this time, too, he had gained expertise in authenticating documents, in part by building on technical analyses undertaken by his staff or by calling for advice from leading experts on handwriting, ink and paper (among them my late friend Tony Cantu, a chief forensic scientist for the FBI). In April 1983, Rendell’s knowledge — and reputation — would be put to the test when Newsweek magazine asked him to look at newly discovered diaries believed to be those of Adolf Hitler. Were they genuine?

Despite authentication by German handwriting experts and the historian Hugh Trevor-Roper, not to mention pressure from German and English publishers, Rendell concluded that the diaries were fake. While the story of this notorious forgery is now well known, Rendell here takes us into his thinking as he was gradually sucked deeper into this complex case. It made him famous, though not always in ways he wished. In subsequent years, he would be asked to analyze the spurious Mormon documents peddled by the murderer Mark Hofmann; investigate the Jack the Ripper diary hoax; and even, to his regret, explain why a set of handwritten lyrics alleged to have been penned by Elvis Presley was a scam.

During these same years, Rendell also appraised Ronald Reagan’s archives and Richard Nixon’s papers, created Bill and Melinda Gates’s library (largely focused on books and documents related to the history of technology), formed a major collection devoted to the American West, and gradually assembled — out of personal admiration for “the Greatest Generation” — artifacts and memorabilia for the International Museum of World War II, widely regarded as the most comprehensive such collection in the world and one that he still hopes can find a permanent home in Washington.

In the later chapters of his memoir, Rendell hobnobs more and more with the rich and famous, regularly flies around the country to dine with potential clients, and even goes on retreats with Silicon Valley moguls. On the advice of his wife and business partner, Shirley — a former television news reporter — he starts to display some of his more glamorous stock at New York’s chichi antiques showcase, the Winter Show. Though Rendell’s admiration for the egregiously successful can sometimes approach that of a fanboy, he also counts many of his customers as real friends: collector and magazine publisher Malcolm Forbes, financier Harlan Crow, John Eisenhower (son of Dwight D.) and distinguished historian Stephen Ambrose.

Overall, Rendell is chary about divulging the selling price of various documents, but he does occasionally reveal some financial details. When, in the 1970s, the federal government seized Nixon’s papers and the White House tapes to be sure nothing was destroyed, the courts eventually determined that the disgraced president was owed compensation. How much? Nixon’s lawyers hired Rendell in 1991 to appraise the value of these documents, initially balking at his consulting fee of $5,000 a day over a two-week period. Quickly enough, though, Rendell realized that what the lawyers really wanted was to extend as long as possible the litigation over the appropriate price for the papers and tapes. Only in 2000 was the case finally resolved, when the government agreed to pay $18 million. As Rendell wryly concludes: “The Nixon Library received $6 million. Federal estate and other taxes amounted to $3.7 million. The Nixon family received less than $90,000. Nixon’s law firm received $7,383,000.”

Besides chronicling an astonishing career not yet over, “Safeguarding History” is chock-a-block with photographs of notable dealers, customers and charlatans; of Rendell’s various offices, located at differing times in Boston, New York, Tokyo and Beverly Hills; and of many of the rare documents he has acquired, including the marriage certificate of Louis XVI and Marie Antoinette, a threatening letter written by Jesse James, and the iconic World War II photograph of the raising of the American flag on Iwo Jima’s Mount Suribachi, signed by three of the Marines in the picture.

Still, it says a lot about Rendell that there are more family photographs than any other kind in “Safeguarding History.” His wife and children have clearly been the sheet anchors of his life. Many of the pictures show his son Jason, who tragically died in an accident at age 18. Others capture this athletic businessman skiing, mountaineering or hiking in Alaska and the West. Even now, at age 80, Rendell still looks trim and ready for new adventures as befits a man once dubbed the Indiana Jones of the collecting world.