It was a black-tie blowout with a guest list as gargantuan as the honoree's ego. A star-speckled cast of friends and fans congregated at Tanglewood in Lenox, Mass., to toast the 70th birthday of Leonard Bernstein, genius, socialite and American music's all-around protean figure. There was Lenny in black cape and white scarf, passionately embracing exiled Russian cellist Mstislav Rostropovich. There was Lauren Bacall, rasping out "The Saga of Lenny," a tune penned by Bernstein's fellow composer, old pal Stephen (Into the Woods) Sondheim. There was the crowd roaring at the "Saga" lyrics satirizing Bernstein's prodigious talents: "Poor Lenny, 10 gifts too many."

There were politicos: Michael and Kitty Dukakis and Secretary of State George Shultz and wife Helena. And there were socialites: Gordon and Ann Getty, Joan Kennedy and Kitty Carlisle Hart. But the Bernstein offspring stole the show. Eldest daughter, Jamie, 36, a songwriter and singer, wrote "The Seven-Oh Stomp" and led her husband, David Thomas, 34, a video distributor, brother Alexander, 33, a teacher, and sister, Nina, 26, an actress, in an a cappella rendition onstage. Bernstein's mother, Jennie, 90, gave her son a Chinese scroll that translated in part: Listen to your mother, stop smoking.

The gala began Thursday with a four-hour concert tour of Bernstein's career. Conductors Seiji Ozawa and John Williams led an orchestra through a medley of such Bernstein legacies as the Broadway and film score from West Side Story. The London Symphony appeared on a video screen playing "For He's a Jolly Good Fellow." On Saturday, music students performed Bernstein's pop-classical pageant, Mass, and on Sunday Bernstein himself took the stage, closing the fete by conducting Tchaikovsky's Symphony No. 5 with his trademark mane-shaking panache.

At the end of the stirring, emotional, at times transcendent weekend of celebration, the festivities seemed appropriate for America's preeminent maestro. After all, one couldn't expect the flamboyant Bernstein to blow out 70 candles at home alone any more than one could expect him to slow down. As the Bernstein brood belted in their homegrown serenade, "Don't you hope you'll have been/Half that cool by three score and 10?" Amen.