The standout songs in John Kander and Fred Ebb’s “70, Girls, 70,” which is being staged in concert this weekend by City Center Encores, are “Coffee in a Cardboard Cup” and “Broadway, My Street.” The first is a vaudeville-style number in which two elderly ladies with low and brassy voices complain that “the trouble in the world today” is that “everything is hurry up.” But lest you think the pace of the modern world is too much for these grannies, the song is delivered in a pounding, fast-and-funny style with a relentless tempo and many murderous modulations. This is a clear tip-off that the authors are dispensing these words with a liberal dose of irony.

While “Cardboard Cup” is a coffee kvetch, “Broadway, My Street” offers a similar message in reverse. Instead of complaining about the present, these two dames, belting a la Sophie Tucker, sing the glories of the past. It’s a rousing show-biz anthem, of the kind that even precedes Irving Berlin’s “There’s No Business Like Show Business.”

Both songs are about the generation gap, and so is the rest of “70, Girls .” The poster for the show depicts a sweet old lady rendered in psychedelic style, and even the title contains a reference that anyone born after 1950 is not likely to get. In the glory days of burlesque, theaters would advertise the quantity of unclad cuties appearing in their chorus line with banners screaming “50 Girls 50!” The gag here is that the “70” refers to the average age of the “girls” in the show.

The constantly shifting nature of cultural tectonic plates is at the heart of most shows by composer Fred Kander (b. 1927) and lyricist Fred Ebb (1933-2004). The pair first worked to gether in 1962 as writers for “The Perry Como Show,” and their first song was “My Coloring Book,” an instant hit written for Sandy Stewart. Their first full-length show, 1965’s “Flora, the Red Menace,” was a flop at first but a success in the long-run in that it launched the careers of Mr. Kander, Ebb, and their star, Liza Minnelli.

A year later, the composers had their first blockbuster, “Cabaret,” one of the mega-musical hits of the 1960s. Their next two shows, “The Happy Time” and “Zorba!” (which both, somehow, opened in 1968) were successful, but “70, Girls” was such a flop in 1971 that Mr. Kander and Ebb weren’t able to get another show on Broadway for four years. That was “Chicago,” which, over the decades, thanks to revivals and the film, has become their most successful property of all.

Like Stephen Sondheim, whose “Follies” opened a few months before “70, Girls,” Mr. Kander and Ebb belonged to a generation that harked back to Rodgers and Hammerstein and the other writers who perfected the integrated story musical during the 1940s. In the late ’60s and early ’70s, after the tidal wave of youth-driven rock music had swept everything away, musical theater found a new faith in classic show tunes and pre rock ‘n’ roll pop music in general.

“Follies,” “Cabaret,” and “Chicago” evoked the 1920s, and even contemporary-sounding works like “Godspell,” “Jesus Christ Superstar,” and “Pippin” had songs that were done in vaudevillestyle double time. Soon, Scott Joplin was on the singles charts, while Fats Waller, Duke Ellington, and Eubie Blake were on Broadway. Retro-styled singer-songwriters like Barry Manilow and Peter Allen were singing of the “Copacabana” and telling us that “Everything Old Is New Again.” And the biggest hit show of the era, “A Chorus Line,” was also the most self-referential, climaxing in an old-fashioned, Busby Berkeley-like dance spectacle.

But with the exception of “Follies,” none of these works addresses the generational shift as entertainingly as “70, Girls,” which is based on a 1958 British play called “Breath of Spring.” That story is about the residents of a senior citizens’ home who take to heisting booty from stores.Their criminal activities serve both as a way of improving their living circumstances and showing the young whippersnappers that they are indeed capable of doing something extraordinary.

The Kander and Ebb musical adds another dimension in that the oldfolks-as-criminal-mob story becomes a play within a play. The framework allows the cast to step out of the plot and treat us to several songs not specifically related to the crime story, but to the nature of aging in general. Among these are the “Broadway” song and “Go Visit,” which rhymes “altercocker” with “shock her off her rocker.” Even within the story, the characters constantly break the fourth wall to cue their pianist. (“Hit it, Lorraine!”)

“70, Girls” is also unique in that there’s no romantic love story at the center of it. Thus the driving momentum of the show’s comedy songs is never interrupted by a love song: It’s just one humorous turn after another. “The Elephant Song” is introduced as a number about death, but it turns out to be that of a pachyderm. “You and I, Love” is marvelously silly and sentimental at the same time, and there are also two mock-religious songs, “See the Light” and “Believe.”

“70, Girls” is the perfect project for City Center Encores. It’s unlikely that any producer would mount a fullfledged revival, even off-Broadway, but “70, Girls” has achieved cult status. The original cast album has circulated widely among music buffs, and a revised version of the show ran to mild success in London in 1990-91. Its snappy songs and jokes make it a show fan’s delight, even if the critics who panned it into oblivion 35 years ago didn’t get the point.

Fred Ebb passed away a year and a half ago at the age of 71, while Mr. Kander, who just turned 79, is working on a musical adaptation of “The Skin of Our Teeth.” I’m anxious to hear what Mr. Kander will say at the traditional Encores seminar following the Saturday matinee performance, and to find out whether his 70s are anything like what he expected back when he was 44.

’70, Girls, 70′ will be performed from March 30 until April 2 at City Center (131 W. 55th Street, between Sixth and Seventh Avenues, 212-581-1212). From April 4 until May 13, Karen Akers will perform a one-woman show titled “First You Dream … The Songs of John Kander & Fred Ebb” at the Algonquin Hotel’s Oak Room (59 W. 44th Street, between Fifth and Sixth Avenues, 212-419-9331).