It's an engaging narrative, this "oral history" of the early years of hip-hop, told in the voices of the people who lived it. Start with a bunch of teenagers in the burned-out South Bronx, writing graffiti on the subways and going to parties at community centers. Disco rules the radio waves, and gang culture rules the streets.

Then in 1973 a Jamaican New Yorker known as Kool DJ Herc begins to organize "disco smokers," charging a 50 cents or a dollar to get in. He makes illustrated fliers to promote his dances, but it's his pronounced taste for what might be called afro-percussive beats that catches the young imagination.

Herc energized something you could call African heritage, something that was made even more manifest with Afrika Bambaataa, another pioneering DJ who affected shields and spears on his fliers and, more importantly, added a progressive political dimension to the music by founding an organization he called the Zulu Nation. A member of the Black Spades street gang, Bambaataa had a vision of taking gang solidarity and using it for a revolutionary cultural uplift.

Still another pioneer was Grandmaster Flash, a DJ with a knack for electronics, a technical wizard who specialized in perfecting his sound system. But Flash was also an artist who could transform looping sounds into a new art form. He also formed the first MC group, putting the guy on the mic out front and making him part of the show -- in his case, forming the Furious Five, the greatest group of the era.

The book showcases many others. Grand Wizard Theodore, the DJ who invented "needle-dropping" at age 14. Sha-Rock, the first female MC, who was probably 15 when she started and who used a big echo effect in her raps. And Love Bug Starski, the DJ who says he was "Rappers Delight," the inspiration for the first breakout rap hit from Sugarhill Records -- allegedly recorded with stolen rhymes not by any of the local stars but by two guys from Jersey and a bouncer from the Sparkle nightclub.

It was not long before Russell Simmons took the Queens rock group Run-DMC and a 16-year-old rapper named LL Cool J to superplatinum status. The sun had set on old-school hip-hop in the Bronx.

Hip-hop was a dance culture. Its focal point was the dance floor. The deejays played their records to excite their core audience of b-boys, who were there to show off their moves. Rap's rhymes came much later.

Admittedly, the subject at hand is not part of what you could call the visual arts. Graffiti, hip-hop's visual dimension, gets modest attention in the book -- a taste of the now-lost artistic innovation of entirely spray-painted trains is given by several photographs, including Martha Cooper's picture of Fab Five Freddy's Campbell's Soup train.

Fans of the "high-low" crossover, too, can find their rewards in Yes Yes Y'all, which is amply illustrated with the homemade fliers -- many done by the celebrated graffiti artist Phase II -- that announced the parties and dances. In many cases, these bits of ephemera, which are often dated, are the only concrete evidence we have that these jams really occurred. The message here is simple -- no matter how quotidian life may appear, history is waiting in the wings.

The book is accompanied by an exhibition of flyers, photographs and graffiti art that opened at Deitch Projects in Brooklyn last November, and since toured to Sandroni Rey in Venice, Ca., and Moniquemeloche in Chicago. The show is currently at the Punch Gallery in San Francisco and finishes its tour at the Experience Music Project in Seattle, which produced both the book and the exhibition.

Jim Fricke, one of the two authors, is curator at the EMP. The other, Charlie Ahearn, made the independent film Wild Style in 1982 and is currently exhibiting his photographs from the early hip-hop scene at Prosper, a gallery on Stanton Street on the Lower East Side, and at Prosper Tokyo in Japan.