Ethan Mordden has been writing decade-by-decade histories of the Broadway musical for about 10 years, though not in anything like chronological order. To further confuse the situation, that "decade-by-decade" description isn't entirely accurate, for his recent The Happiest Corpse I've Ever Seen roughly covered the period from 1980 to 2003; there just wasn't enough happening in the '80s and '90s to warrant separate volumes. But for those of us who count on Mordden for his exhaustive research, lucid analysis, and witty prose, coverage of one seemingly essential decade has gone wanting -- till now.

Sing for Your Supper: The Broadway Musical in the 1930s (Palgrave Macmillan, 270 pages, $26.95) not only fills in the missing years but wastes no time in explaining why Mordden didn't get to them sooner. On page one, he calls the '30s "the most difficult decade in the set: the one that left the fewest remains behind for the archeologist, whether as filmed souvenirs of its performing styles or the simple survival of scripts and scores" -- and, a couple of paragraphs down, "the least enterprising decade in the musical's Golden Age." That may come as a shocker for armchair musical historians. Didn't the '30s bring us shows by Rodgers and Hart, Cole Porter, the Gershwins, and Jerome Kern, plus the musical agitprop of Marc Blitzstein and early Harold Rome, not to mention the prized revues of Arthur Schwartz and Howard Dietz?

Well, yes, Mordden explains -- but there's less here than meets the eye. Depression-ravaged producers vastly reduced their output; the 1927-28 season had yielded 53 new musicals, while production rates in the mid-'30s drooped to levels not much higher than today's. Profit margins were cut and runs were greatly curtailed: A smash hit, like the Jerome Kern-Otto Harbach The Cat and the Fiddle (1931), survived less than a year. Operetta all but died off, a victim of high budgets and low critical and public esteem. Musical comedy, which had made some developmental strides in the '20s, became more formulaic than ever: Even 1931's Of Thee I Sing, the first musical Pulitzer Prize winner, "was a babes-and-jokes show, albeit of unusually high satiric quality." Revues did thrive and become more unified and thematic, offering something like a cogent worldview; but the very ephemeral nature of the form, with timely jests and much material that hasn't survived, makes it tough to analyze.

Given that Mordden previously plowed through the '20s in his excellent Make Believe, it's a surprise to hear that even less survives of the '30s. Good detective that he is, he nevertheless uncovers plenty. And a lot of it is fascinating. Take operetta: Was it really such a washout? How about May Wine (1935), a fairly long-running Sigmund Romberg-Oscar Hammerstein II concoction that emcompassed attempted spousal murder, psychoanalysis, ménages a trois, and a most un-Romberglike penchant for blue notes? Or Virginia (1937), with the usually pop-song-oriented Schwartz dabbling in the American Revolution and operetta forms with distinguished playwrights Laurence Stallings and Owen Davis? The piece sounds worthy of attention, though Mordden posits, "something tells me the people at Encores! would give a season of The Black Crook, It Happens on Ice, and Dance of the Vampires before they'd get to Virginia." Other operettas tended to revert to formula -- a staggeringly high proportion of them dabbled in three-generation romances, à la 1917's Maytime -- and even the form's masters, such as Romberg and Rudolf Friml, were less musically inspired than they had been the decade before.

But formula was even more pervasive, and the writing less ambitious, in musical comedy. The standard entertainment was a star-comic vehicle like Flying High (1930), with a disposable De Sylva, Brown, and Henderson score and only enough book to allow Bert Lahr to cavort. The dialogue snippets that Mordden quotes from this and other specimens reveal that comedy writing has made huge strides in 75 years, and the song titles sound uninspired and interchangeable. That, he writes, was "the worst aspect of thirties musical comedy, generic posing that gives no taste of character." Of course, the decade's star power was formidable: not just Lahr but also Fanny Brice, Fred Astaire, Ethel Merman, Sophie Tucker, Bob Hope, Jimmy Durante, Ed Wynn, and Dennis King, to name a few. But the vehicles they trafficked in were largely undistinguished and indistinguishable. Their supporting casts and characters were standard-issue, bland juveniles and ingénues, often vocally underpowered. Even William Gaxton, a leading man associated with several of the decade's classic titles, turns out to have been a charmless boulevardier with hardly any singing voice.

The decade did throw off two significant innovations, Mordden writes: improved stage technology, most notably the revolving stage (or, as in 1931's groundbreaking The Band Wagon, the double revolve), and choreography that aspired beyond the typical '20s hoofing chorus. George Balanchine dominated the decade's latter half with high-powered Rodgers and Hart shows such as On Your Toes and The Boys from Syracuse, while Agnes de Mille got her start in throwaways like Hooray for What! Even in these instances, though, the progress is sometimes overrated: Balanchine's "Slaughter on Tenth Avenue" ballet, in On Your Toes, has an undeserved reputation for integrating dance and plot, and his celebrated "Roxy Music Hall" sequence from I Married an Angel is a complete diversion from plot and theme. Swing and jazz dancing, especially in all-black-cast musicals, round out the decade choreographically -- energetic and enjoyable, but not noticeably about anything.

If you do have a working knowledge of the decade, you'll have a good time arguing with Mordden's opinions and occasional prejudices. He's needlessly rough, as he is in other volumes, on Blitzstein, finding him "a fascinating yet ultimately incomplete talent" and an incompetent melodist. He finds the Rodgers and Hart scores of the decade "very much alike in the way they delineate character and in overall musical construction," and he seems to find this a flaw as measured against the greater variety in Porter and Gershwin scores. (Like there's something wrong with The Boys from Syracuse?) He writes that Kern's Cat and the Fiddle "may well be the most integrated score of all time," but he rather slights Kern and Hammerstein's work on the following season's Music in the Air, a show with a masterpiece of a score and a bright, witty book (you'll just have to take my word for it). The way Mordden sees it, ultimately, the decade's real hero is Cole Porter -- for his sexual frankness, his veiled but accessible gay sensibility, his musical adventurousness, and his individuality. All of that is undebatable, but is Anything Goes (1934) truly the decade's one indispensable work (save Porgy and Bess) and is it really a "message" show? For, Mordden it is, the message being: "the glamour of celebrity has overwhelmed everyone's moral judgment." (He has done some great sleuthing on the history of the show; that story you read in every other history about the sinking of the Morro Castle necessitating a new libretto for Anything Goes turns out to be bunk.) Is Jubilee (1935) really the most overlooked great musical of all time? Isn't it possible to savor Porter's work without considering everyone else somehow second-rate?

Mordden makes some other minor faux pas. He miscounts the intervals between years not once but twice (in reference to Anything Goes and The Dubarry). Disappointingly, he's unable to come up with anything new to say about Porgy and Bess. Yes, it's uncategorizable; it was a victim of musical snobbery; it's unfairly characterized as "racist" in some quarters. But we knew all that. His mild approval of Irving Berlin's Face the Music score fails to mention the scathingly brilliant "Investigation" finale, unlike anything else that Berlin ever attempted. And, always eager to show off his technical knowledge of music, Mordden includes terminology that will confuse anyone who isn't a conductor or a musicologist.

On the other hand, there's a great deal of good stuff here. Given the decade's paucity of product, Mordden spends more time than usual discussing film versions, concert versions, and obscure revivals of shows; if you ever wondered about the '80s Equity Library Theatre productions of Nymph Errant or Very Warm for May, you can read about them in this book. One crack about Astaire's "Night and Day" dance aside, Mordden has cut down on the vulgarity-for-shock's-sake prose that marred some of his previous volumes. Most gratifyingly, he has unearthed titles that have been ignored for decades but sound worthy of rediscovery if not fully staged revival. Ever heard of Jerome Moross's Parade (1935)? Friml's Luana (1930)? Want to learn more than you ever thought possible about Kurt Weill's Johnny Johnson (1936) and Knickerbocker Holiday (1938)? Like to know how terrible the dialogue of Revenge With Music (1934) is? It's all here.