At our present level of musical enlightenment, everyone knows what ragtime is. It is Gunther Schuller conducting a group of student virtuosos as though he were John Philip Sousa having a bit of fun at the local pub; Max Morath playing Joplin on the piano as though the music had originally been written for a banjo. Above all, perhaps, it is the soundtrack of "The Sting," which may have gotten an unearned Oscar for Marvin Hamlisch but also made Scott Joplin's name, very belatedly, a household word.

To the purist, ragtime is something rather more restricted; it is classical piano music, composed by Joplin, Artie Matthews, Joseph Lamb and a few others. It may be based on some rather regrettable 19th-century song and dance forms, as Chopin's mazurkas and polonaises were based on Polish popular music, but in its classic state it has nothing to do with singing or dancing. The epitome of purist ragtime is Joshua Rifkin playing Joplin exactly as it is written -- with particular attention to the often-repeated instruction, "Not too fast." The experience is as decorous as it is melodious -- and as far as we can tell, it was the way Joplin wanted it done, though it is certainly not the only way it can be done.

Some segment or combination of the elements above has become the standard idea of ragtime music since it became a hot musical commodity in the "second ragtime revival." These descriptions may in fact cover the best and most permanent aspects of ragtime, but as Edward A. Berlin documents in great detail, they are only a small part of what people were calling "ragtime" during the ragtime era. In this feverish quarter-century (roughly from 1895 until 1920), ragtime conquered the field of popular music, first in the United States and later in Europe; it inspired classical composers as varied as Debussy and Stravinsky. The public took it to its bosom and, as usually happens when millions of people are enjoying something, talking about it, writing about it and (perhaps most important of all) buying it, things got muddled. When a title is good for sales, it is likely to be used without too much care for fine distinctions.

During the ragtime era, the name was used mostly for vocal music -- and often for vocal music that imposed hideous racial stereotypes on the black people who were the inventors of ragtime. Ragtime was confused with foxtrots and cakewalks and polkas and even waltzes, and perhaps more understandably with the later-emerging, related but distinct forms of blues and jazz. The name was applied to music that used dotted rather than syncopated rhythms, and it was applied to the music of men such as Irving Berlin, who was a fine composer but not a ragtime composer.

There is a certain richness, as well as a certain confusion, in the jumble that went under the name of "ragtime" when the name was new and imperfectly understood. Berlin, who has a doctorate in musicology, manages to preserve the richness while sorting out the confusion in a work that often reads like a spruced-up doctoral dissertation but manages always to preserve lucidity, even when style is sacrificed to thoroughness and precision. Besides reading and analyzing an appalling quantity of sheet musci, most of which was inevitably mediocre, he has examined exhaustively the printed and recorded information on how ragtime was discussed, promoted and performed during the ragtime era. After reading his book, one may feel free to go back to the emotional conviction that real ragtime is Scott Joplin played by Joshua Rifkin -- but it will be done with an awareness considerably expanded by the reading.

The latter portion of Berlin's book, where he examines the varieties of syncopation, the formal structures of ragtime piano compositions, the stylistic development and decline of the art in its 25-year heyday, will be of interest primarily to specialists.

For the general reader, there is considerably more interest in the earlier section, where he examines the cultural background and ventures into types of music that are practically forgotten now but were intimately associated with ragtime before it became a classical form. The first printed sheet music that can be identified as ragtime in style occurs actually in the accompaniment of a "coon song," a genre happily long out of style whose content was precisely what its generic title would indicate. Even the names of most coon songs tend to be offensive to modern sensibilities (probably the best known was "All Coons Look Alike to Me"), and Berlin's summary of the usual content of these songs (some of which were the works of black composers struggling in a white market) is eloquent in a scholarly sort of way: "Generally, the themes of coon-song lyrics can be summarized as: violence (especially with a razor), dishonesty, greed, gambling, shiftlessness, cowardliness and sexual promiscuity."

An effort was made, through the years, to evolve the coon song into something with more positive ethnic overtones -- James Weldon Johnson played a significant role with lyrics such as those of "Under the Bamboo Tree." The story of the development from gross caricature into songs such as "Everbody Calls Me Honey," "Darktown Strutters' Ball" and the kind of music associated with Al Jolson and Bert Williams would make an interesting book in its own right, but that is another story.

Berlin also chronicles the controversies that raged around ragtime as it became popular -- controversies that involved the quality of the music, the question of whether it should be identified as "American," whether it could be part of the root system for a distinctively American classical music, and (symptomatically) whether credit for inventing it could be given to any group as low-down and shiftless as American blacks. One of the most interesting cultural notes in his two-pronged book actually occurs deep in the musicological section, where he reprints a series of sheet-music covers showing the changing image of ragtime as it became "respectable." The genre begins with plantation-style caricatures on its covers, modulates into the "Peaches and Cream" rag (1905) with a beautiful young woman (white, naturally) on its cover and reaches some kind of climax with the "Encore Rag" (1912), whose cover shows ragtime being played in an all-white salon setting, with the men in white tie and the women in formal dresses.

In one dimension, which Berlin sketches and partially fills in, the story of ragtime is the story of America's assimilation of one of the most vigorous and creative elements of our population into our cultural mainstream; it impinges on the story of how a new American identity, distinct from our partially European origins, was forged and is still being forged. That assimilation is still incomplete. Some predominantly black television situation comedies might be analyzed as the latest successors to the coon-song tradition, and their content compared with that of the coon songs ad an index of how far we have come. Another index is the way ragtime music is regarded today, compared with the attitudes that surrounded its origins. By providing the material for such a comparison, Berlin has given us a handle on how far we have come and how far we still have to go.