There is something irritating about the very premise of Girls Like Us, Sheila Weller's three-headed biography of legendary singer-songwriters. Maybe it's the instant-girlfriend tone of the title. Maybe it's that at least one of Ms. Weller's subjects, Joni Mitchell, objected to being lumped into the same book with the other two, Carole King and Carly Simon. Or maybe it's the euphemism. Her book is about women whose musical careers took off in the 1960s, and all are now in their 60s. They aren't girls. They're grandmas.

But Girls Like Us turns out to be unexpectedly captivating. And it defies expectations, to the point where Ms. Weller's grand ambitions wind up fulfilled. When woven together, she writes, predictably summoning Ms. King's image of a tapestry, the strands of their three separate lives, identities and songs tell the rich composite story of a whole generation of women.

Never mind that nobody asked Ms. Weller to do this weaving. Never mind that her book has a tendency to gush and fawn. She has still put it together in revelatory ways, underscoring the generation-wide impact of her subjects' songs and stories. As Elliot Roberts, Ms. Mitchell's longtime manager, once put it, this was a matter of people being guided by your music and using it for the soundtrack for their lives.

Girls Like Us is a strong amalgam of nostalgia, feminist history, astute insight, beautiful music and irresistible gossip about the common factors in the three women's lives. Much of the overlap has to do with these women's ties with certain men. I was his new queen, says Ms. Simon, the only one of the three who cooperated with Ms. Weller, about how James Taylor passed from Ms. Mitchell's life into her own, and Ms. Mitchell was Anne Boleyn on her way to the Tower.

But if Girls Like Us presumes its way onto a first-name basis with lovers and compatriots like Cat, Mick, Warren, Jackson, Kris, Leonard and James, it also has a point to make about sexual inequality in the era when these three women came of age. The ambition and posturing that turned middle-class Robert Zimmerman of Minnesota into Bob Dylan, Ms. Weller argues, were much more costly for women, no matter how freewheeling those women seemed. This book illustrates how Ms. Mitchell's long-held secret about the baby she gave up for adoption was infinitely more punishing than the rambling, gambling male singer-songwriter's stock way of paying his dues.

Given the drastically different backgrounds and personalities of her subjects, Ms. Weller creates a remarkably smooth synthesis. Frequently citing songs and quoting lyrics, she establishes how the assertively homey style of Ms. King (who was a pregnant bride at 17 ½ and a chart-topping songwriter not long after) and Ms. Mitchell's traveling, traveling, traveling, for instance, were both ways to establish strong public personas. And Ms. Weller segues neatly from the fictional melodramas watched by the young Ms. Mitchell (then Roberta Joan Anderson) on Canadian movie screens to the real-life ones unfolding in Ms. Simon's privileged, sexually overcharged household in Riverdale in New York.

Though Girls Like Us covers vast spans of time and territory, Ms. Weller comfortably evokes many different milieus. It was embarrassingly unfeminine in 1961 to be a piano-banging, moon/June rhyming argumentative workaholic, she writes of Ms. King in Brooklyn.

The mid-1960s liberal arts college girl like Ms. Simon is described as a polished young woman from a family of means, who wore an expensive suede jacket and hoop earrings, with the sides of her shiny long hair gathered at the back of her head by a wooden-chopstick-clasped leather thong. And of Ms. Mitchell and other butterfly bohemians: The day you first started seeing your peers dressed in clothes from other centuries (had people ever done this before?) was the day that Dylan's lyric 'Something is happening and you don't know what it is, do you, Mr. Jones?' took on a sharp, delicious significance. Corny, but true.

In addition to the acuity about style that is one of its selling points, Girls Like Us also notes the cultural landmarks of its heroines' heyday. There are books like Loose Change and The Cinderella Complex and My Mother/Myself; there is Kramer vs. Kramer as it redefined marriage. There is Laurel Canyon in Los Angeles, once home to Ms. Mitchell and Ms. King, celebrated in song and story and now roundly acknowledged as this generation's version of 1920s Paris. And there is the goat-milking life in Idaho to which the much-married Ms. King retreated with her fourth husband. (Her story is easily the book's most surprising. According to this book's acknowledgments, Ms. King is trying to write a book of her own.)

Carole King's quiet embrace of the rugged West was much more authentic than, say, the Hollywood Hills-dwelling Eagles' photo shoots among parched coyote skulls, Ms. Weller writes. As that makes clear, she can sharply underscore her book's central contrast between challenges facing women and those facing men.

Yet for all her interest in larger themes, Ms. Weller constantly risks sounding like a besotted fan. And for that the reader owes her a little debt of gratitude. She has both the nosiness and the temerity to track down the stories behind well-known songs. While it may be crass to wonder which of the era's famous men with the lanky, chiseled looks of Civil War soldiers was Ms. Mitchell's Coyote in the song of that name, here's an answer anyway: Sam Shepard, around Bob Dylan's 1975 Rolling Thunder Revue. Since Ms. Weller has some of this information second hand, it's hard to know how reliable she is. But the sources she pursued even include one of Mr. Taylor's drug dealers. So she has been nothing if not aggressive in her digging.

Girls Like Us is best read with its stars' celestial hits as an accompanying soundtrack and with a new open-mindedness about these stories. At long last it's time to acknowledge that even if women who enjoyed that glamorous little wedge of early 1970s feminism - between the fiercely anti-'sex object' early feminism and the so-called padded-shoulder 'power suit' feminism of later years - would have cited Billie Holiday as a great female artist, it was Ms. Simon whose life and issues more closely matched most of their own.