It was 50 years ago last month that Gershwin died. As was the case in 1973, the 75th anniversary of Gershwin's birth, orchestras in Europe as well as in this country are making Gershwin material a staple of their summer fare.

At least three Gershwin specials are scheduled for public television in the next few months, beginning with a 90-minute documentary set to air on Aug. 24. So far this year there's been only a trickle of new Gershwin recordings, but several labels have major Gershwin packages planned for the Christmas season. Edward Jablonski's new Gershwin biography is already in the hands of reviewers, and more publications are on the way.

It's good that this flurry of activity is happening. No matter how deeply Gershwin's music has been ingrained in the fiber of American life, doubtless there are some among us who still take it for granted. If nothing else, the high profile given the Gershwin oeuvre in this anniversary year is a reminder - for those who need it - of how great his contribution to our culture really was.

Gershwin was only 38 when he died, and there's no telling what he might have produced had he not fallen victim to a brain tumor while in Hollywood working on a score for the movie titled ''The Goldwyn Follies.''

His plans, at least, included a second full-length opera, a string quartet, a ballet, another piano concerto and a classically structured symphony. His phenomenal success with commercial music notwithstanding, what he longed for most was recognition as a ''serious'' composer.

''I haven't yet scratched the surface in music,'' he told his sister during that final sojourn in Hollywood. He was right.

The amazing thing about Gershwin is how much he did manage to accomplish with so relatively little formal training.

His fans may protest, but Gershwin, I think, can accurately be called only one of America's greatest songwriters. Granted, I'm tempted to bestow the full title on him - without qualification - every time I'm caught up in the smooth flow of ''Embraceable You,'' ''Someone To Watch Over Me'' and other of his perfectly designed ditties. But when the music fades, somehow I remember that there was also Berlin, and Cole Porter, and Jerome Kern, and Harold Arlen, and Richard Rodgers.

Of these superbly gifted tunesmiths, though, only Rodgers shared with Gershwin the urge to write music for the concert hall. He was better equipped for it, for - unlike Gershwin - he actually studied composition and music theory in college. Rodgers' efforts were noble and numerous; they include a ''symphonic narrative'' commissioned jointly by the Philadelphia Orchestra and the Paul Whiteman Band, several ballets and a symphonic suite based on the music from the 1952 film ''Victory at Sea.''

Aside from ''Victory at Sea,'' however, Rodgers' works are hardly ever performed these days. Even if they were performed, they would have to share billing with someone other than Rodgers; again unlike Gershwin, but very much in keeping with the practice of Broadway composers, Rodgers never bothered to orchestrate his material.

The question of orchestration comes up often in Jablonski's new ''Gershwin'' (Doubleday; $21.95).

As he and co-author Lawrence D. Stewart did in their 1958 ''The Gershwin Years,'' Jablonski offers plenty of evidence to debunk the myth that - with the exception of ''Rhapsody in Blue'' - Gershwin did not orchestrate his own concert pieces. And one of the book's principal themes - far more obvious here than in ''The Gershwin Years'' - is the argument that Gershwin's orchestrations are infinitely superior to the versions familiar to most listeners today.

''Rhapsody in Blue'' does not enter into the debate, for it is well known that Gershwin wrote it only in so-called ''short score,'' that in all three of its performable incarnations - for jazz band, for small orchestra, for full symphonic orchestra - the instrumentation is the work of Ferde Grofé.

What is not so well known is that ''An American in Paris'' is typically heard in a score brought out by New World Music Corp. after Gershwin's death and substantially revised by Frank Campbell-Watson, one of the publishing house's music editors. The ''Concerto in F'' is likewise most often heard in the revised version by Campbell-Watson; the standard orchestrations of the ''Second Rhapsody,'' the ''Cuban Overture'' and the '' I Got Rhythm' Variations'' are by Robert McBride, Albert Coats and William C. Shoenfeld, respectively, all of whom did their work at Campbell-Watson's request. (The popular ''Porgy and Bess - A Symphonic Picture'' is, of course, an always credited arrangement by Robert Russell Bennett. Bennett, W illiam Daly and others, however, were usually not credited for the adjustments they made to the ''Porgy and Bess'' score that was used in opera houses between 1938 and 1975.)

Jablonski is passionate, almost to the point of sounding like a bleeding heart, when he denounces Campbell-Watson for tampering with Gershwin's original scores. But all one has to do is listen to those several of the originals that have found their way onto disc to know that Campbell-Watson was doing Gershwin's legacy a favor.

For example, the ''Catfish Row'' suite from ''Porgy and Bess'' - premiered under Gershwin's direction in 1936, then dormant until 1958 and first recorded, in 1974, by Leonard Slatkin and the St. Louis Symphony (Vox VSBX-5132) - is pallid stuff indeed, and not just when compared with the work of virtuoso orchestrators such as Bennett.

The not-often-performed ''Second Rhapsody'' is a lot thinner, and much more predictable in its reliance on old-fashioned pit orchestra sonorities, in the original 1931 version recently recorded by Michael Tilson Thomas and the Los Angeles Philharmonic (CBS IM-39699) than in the McBride edition.

The vintage ''American in Paris'' (recorded in 1929 under Gershwin's supervision, re-issued by RCA on AVMI-1740) is an invaluable document, of course, but the instrumental combinations sound almost amateurish in the light of Campbell-Watson's splashy, flashy treatment.

So Jablonski's argument doesn't stand up when it's put to the aural test. Actually, it fails even before one goes to the record library, for another of the book's main themes is Gershwin's awareness of his orchestrational shortcomings.

The quotations from Gershwin's letters are many and lengthy. Again and again we find him telling a friend that slowly but surely his ''skills are improving,'' that the orchestration of one or another latest effort is ''the best I've ever done,'' that he's ''continuing to work at it.'' In fact he did work at it - and work hard - especially after the 1924 ''Rhapsody in Blue'' brought fame, fortune and ambition his way.

Gershwin wanted to be able to do it all on his own. He gave it his best shot, and he was sorely wounded when, in 1932, the author of an article in the American Spectator magazine wrongly claimed that Gershwin had himself scored none of ''An American in Paris'' or the ''Concerto in F.''

But he was starting almost from scratch.

Although he had been taking private lessons in harmony and composition ever since he was a teen-ager, as late as 1925 - prompted by a commission from Walter Damrosch to write the ''Concerto'' - he needed to go out and buy a book on orchestration in order to learn how instruments other than the piano functioned.

Even in his final years, Gershwin worried about not being able to ''hear'' the sounds of instrumental combinations and voicings in his mind. Everything he wrote he wrote first for piano; the scoring came later, usually after long months of trial and error.

Some people feel that to be a composer - a real composer - one must also be a good orchestrator. Perhaps that's why the Irving Berlin comment cited above is typically given with quotation marks around the final word.

Perhaps that's why Jablonski is making such a big deal of all this, in order to win ''official'' acceptance of Gershwin by convincing us that - contrary to the aural evidence - Gershwin was some kind of orchestrational genius.

Gershwin was a genius, and the fact that his musical abilities were in some ways limited need not detract from his stature.

He couldn't do much with sonorities once he got away from the piano. But he knew how to write exquisite tunes, how to shade them with scrumptious harmonies, how to give them just the right rhythmic touch, how to order them in ways that make perfect sense.

He wanted very much to study with the French pedagogue Nadia Boulanger, and he was disappointed when Boulanger rejected him on the grounds that an academic approach might spoil his "natural gifts." He sought lessons, too, from Igor Stravinsky. "How much money do you make per year?" the Russian master asked his would-be acolyte. Upon hearing the answer, Stravinsky said: "In that case, sir, I should study with you."

The meetings with Boulanger and Stravinsky took place in the spring of 1928, by which time the 29-year-old Gershwin was a fabulously successful musician who counted his income in six figures.  His forays into the concert hall had hardly gone unnoticed. "Rhapsody in Blue" won acclaim from the moment of its premiere early in 1924; the next year's "Piano Concerto in F Major" - commissioned by conductor Walter Damrosch for the New York Symphony Society - took off on a comparably fast track, and the violinist Samuel Dushkin was making a habit of including an arrangement of "Short Story" on his recital programs.

But Gershwin would have been the first to admit that his growing fame and enviable financial situation had little to do with his serious work. It would bother him for the rest of his life, but he recognized that at heart he was not so much a composer as a tunesmith. Almost dismissively, he granted that writing for the theater was "agreeable and remunerative." The fact is, the theater was his natural milieu.

The hundreds of songs that Gershwin turned out for the Broadway stage and, later, for Hollywood include more than a few that will rank permanently among pop music's all-time greatest hits. They are "standards," durable yet infinitely malleable. It is precisely because they lend themselves to highly personalized stylings that we almost never hear them in their original settings. For those who think they know their Gershwin, the new recording of "Lady, Be Good!" (Nonesuch Electra 79308-2) is a real ear-opener. 

This is the third in a series of Gershwin restorations by Tommy Krasker, a Gershwin scholar whose previous efforts for Nonesuch focused on "Girl Crazy" and "Strike Up the Band." It was completed in 1991, four years after a production at the Goodspeed Opera House in Connecticut suggested that a revival of the original materials could indeed be stage-worthy. But piecing it together was no mean feat, for a more or less official version of the score never existed.

"Lady, Be Good!" had an uncommonly long run after it opened in November of 1924, and it was in the nature of the show that its most crowd-pleasing numbers be changed according to who was in the cast at any given time. The song called "Jazz Little Bird," for example, was designed especially - and exclusively - for the vaudeville star Ukelele Ike; when Ike dropped out in 1925, so did the song. Another novelty routine, the dance-propelled "I'd Rather Charleston," did not enter the show until after the Charleston craze erupted in 1926.

The show was "a perpetual work-in-progress" whose "only constant was its success," Krasker writes. The recording thus "embraces elements from all stages of its development," he says, and in his introductory essay he neatly documents the sources from which those various elements have been gleaned.

In spite of its patchwork essence, "Lady, Be Good!" as presented here seems both complete and consistent. Krasker's digs through the archives uncovered original orchestrations for only six of the 18 numbers; for the others he had to rely on piano-vocal scores, rough manuscripts and vintage recordings, but apparently this was enough to put his arrangers quite in tune with their predecessors. Just as there are no appreciable sonic differences between the charts produced in 1924 by - among others - Max Steiner and Robert Russell Bennett, so are there no obvious gulfs between the original orchestrations and the fresh ones penned by Larry Wilcox and Russell Warner.

The only tunes from "Lady, Be Good!" that have enjoyed glorious careers of their own are the title song and "Fascinating Rhythm." But everything in the show benefits at least a bit from Gershwin's golden touch; heard in context of a quasi-authentic performance, the material goes a long way toward explaining the Gershwin phenomenon.

"Lady, Be Good!" was Gershwin's first full-length collaboration with his lyricist brother Ira and his first involvement with the dancers Fred and Adele Astaire. More significant, it was his first Broadway smash.   Audiences of the time were used to gentler fare; in fact, the other two big hits of the 1924 season were Rudolf Friml's "Rose Marie" and Sigmund Romberg's "The Student Prince." Compared to the precious sentimentality of those operettas, the new Gershwin opus had the effect of a loud-mouthed flapper crashing a tea party. It was sassy and saucy, as brash in its humor as anything Broadway had ever experienced. "Lady, Be Good!" was the theatrical calling card of the Roaring '20s, just what New York's "smart set" had been waiting for.