In the tradition of musical families through the centuries -- the Bachs, Mozarts, Menuhins and the Busch-Serkin clan come to mind -- the National Symphony concert at Wolf Trap on Saturday night was all in the family. The size of the huge crowd that gathered to enjoy the music was an indication of the popularity of the whole idea.

With Mstislav Rostropovich conducting, the stage was peopled with a father and two daughters, a son-in-law, a husband and wife, a pair of brothers, and two brothers-in-law.

Daughter Elena Rostropovich was soloist in the Mendelssohn G Minor Piano Concerto No. 1, not the No. 2 in D Minor printed in the program. (The program also gave an 8:30 starting time, though the tickets read "8 p.m." The music began around 8:15.) The brief lyrical portions of the concerto had a pleasing singing tone, but the amplification made the young pianist's touch sound somewhat more brittle and detached than it might actually have been.

For the Beethoven Triple Concerto Rostropovich was joined by daughter Olga, her husband, pianist Alexander Peskanov, and the pianist's violinist brother Mark. Here was a reading filled with all kinds of subtle nuances. For those frequent moments in which the solo violin and cello join in intimate passage work, violinist Peskanov turned directly toward his sister-in-law cellist in order to let their close-intervaled lines achieve a special unity and brilliance.

Meanwhile, pianist Peskanov was playing with a mature beauty, shading every phrase with nuance of rare refinement, while providing an ideal sonority and exquisitely poised scales.With such companions, Rostropovich and the orchestra offered something like ideal support.

The program began with a fiery reading of the Roman Carnival Overture of Berlioz, played in a manner that made you glad the orchestra is taking it on its visit to South America this week. Richard White's English horn solo was a marvel, and the buildup at the end, with the trumpets and trombones blazing away, was a knockout. Bon voyage!