Steve Martin once performed stand-up comedy at a drive-in theater where audience members expressed amusement by honking their horns. That's not a conceptual joke from an old Steve Martin routine—it actually happened.

It's hard now to picture the king of anti-comedy—a natural who seemed to glide to rock-star fame in the 1970s with a deranged grin on his face and an arrow through his head—slogging through a long, winding, grinding show-business climb. Certainly by the time he was doing "King Tut" on Saturday Night Live in 1978, Martin had shed any visible traces of his ordinary, frugal, somewhat unhappy childhood under the LAX flight path in Inglewood, California. His comedy was mercifully free of personal-pain-as-punchline material; his most famous routines were sly, absurdist, and, above all, joyous. Now, at 62, Martin—art collector, writer, and movie star—is one of Hollywood's more enigmatic celebrities, a reserved, cerebral man who on screen can impersonate the biggest idiots and blowhards on earth.

Born Standing Up (Scribner) is his latest book, and it's not a novel or a collection of New Yorker humor pieces. It's a slim, economically worded memoir of his early days as a comedian. There are some personal revelations, including how he lost his virginity to a singer named Stormie Sherk: "I was a late-blooming 18-year-old when I had my first sexual experience, involving a condom (swiped from my parents' drawer) and the front seat of my car." But rather than write a lurid Hollywood tell-all or therapy-driven voyage of self-discovery, Martin has taken a lucid, good-humored, and somewhat dispassionate look back at the larval stages of his career—not an autobiography so much as a chronicle of, as he puts it, "someone I used to know." If anything, Born Standing Up is disarmingly understated, a show-business version of Robert Graves's World War I memoir, Good-bye to All That.