According to Billboard chart statistics, Chicago is second only to the Beach Boys as the most successful American rock band of all time, in terms of both albums and singles. Judged by album sales alone, as certified by the R.I.A.A., the band does not rank quite so high, but it is still among the Top Ten best-selling U.S. groups ever. If such statements of fact surprise, that's because Chicago has been singularly underrated since the beginning of its long career, both because of its musical ambitions -- to the musicians, rock is only one of several styles of music to be used and blended, along with classical, jazz, R&B, and pop -- and because of its refusal to emphasize celebrity over the music. The result has been that many critics have consistently failed to appreciate its music and that its media profile has always been low. At the same time, however, Chicago has succeeded in the ways it intended to. From the beginning of its emergence as a national act, it has been able to fill arenas with satisfied fans. And beyond the impressive sales and chart statistics, its music has endured, played constantly on the radio and instantly familiar to tens of millions.