Act One

A young couple, unmarried college students, Danny and Lizzie, are moving into their basement apartment off-campus ("We Start Today").

The oldest of the three couples, Alan and Arlene, both in their forties, are recovering from too much champagne the night before, when they were celebrating their wedding anniversary. Reflecting on their middle age and their grown children, they, too, can now look forward to the future.

The third couple, both 30-year-old gym coaches, Nick and Pam, are in bed, discussing their urge and need to procreate, eventually crawling back under the covers.

The lights dim, and we hear the sound of an embryo's heartbeat. All three women are astonished. Each moves to her mate. The young college couple is stunned. The oldest pair is dubious. The jocks are joyous.

Danny and Lizzie discuss taking the step of getting married. He reasons that they should. Her reasoning: if they never marry, they'll never divorce ("What Could Be Better?"). In self-congratulatory fashion, they contemplate what musical talents, what looks, what brains the little one might inherit from two perfect specimens like themselves.

Alan and Arlene, dressed in jogging outfits, are exercising. They attempt to recall the night that they celebrated their anniversary with champagne (a whole bottle?) Well, she remembers, bottles number "one and two / I do recall / Three and four I don't recall at all." Alan is joyful and finds the prospect of a new family exciting. Arlene is concerned, perhaps a bit horrified, because of her age ("The Plaza Song").

Nick and Pam are pleased and giddy about their conception success ("Baby, Baby, Baby"). They are bolstered by the news because she thought that her athletic prowess made her unfeminine, unmotherly. Lights come up on Alan and Arlene dancing the cha-cha. As they are dancing, lights shift back to Nick and Pam as she remembers being teased as a tomboy when she was a child, but now she can prove that she's a woman and a mother.

A student ensemble injects commentary on Lizzie's condition, considering that maybe she's just lonely or flunking or crazy or Catholic... while she is speaking with her anxious mother on a pay phone. The scene shifts to the doctor's office, where all three expectant mothers meet. Pam is eagerly enjoying her pregnancy. They exchange details on themselves and their mates. Lizzie has every practical step of the way mapped out: an extension for her classwork, a postponement on assignments when she's to give birth, the advantages of nursing the baby ("free food") and, after three weeks, back to class with the kid – if need be – in a back pack ("I Want It All").

As dads-to-be, Nick consoles Danny, who wants to marry Lizzie, and advises him to give her air and give her space ("At Night She Comes Home to Me").

Danny itemizes his "history" of playing punk rock, dying his hair and wearing a nose ring, but now, when he expresses his desire to marry Lizzie for the child's sake, he's considered peculiar and out of step. The scene ends with a quick cut to an angry Pam slamming her basketball down after being told that her condition is not what she had hoped. She's not pregnant after all. Files got mixed. Crushed, she melts into her husband's arms.

Danny pleads with Lizzie for them to marry. When she refuses, he realizes that he must take the job that he was offered with a punk rock group (which he hates) in order to support them and their child out of wedlock.

Once again, the student chorus chimes in and comments on the passage of time. Now it's May.

Pam, now determined to find out what's wrong with her, why she cannot conceive, has decided to see a specialist. Cut to the doctor's office. The physician is adjusting to his new contact lenses and acts more like a patient than his patient. But the real patient, it seems, is not Pam, but Nick, who (after the doctor analyzes the sperm count) is "shooting duds." The physician suggests a strict regimen for their sex life as the scene fades.

Danny bursts onto a baseball field during a warmup among faculty members, wearing a punk costume and announcing that he has joined a band for a summer-long gig that will allow him to make "big bucks" for his kid ("Fatherhood Blues").

Despite his happiness at the prospect of being a father again, Alan understands Arlene's hesitancy of going through with the birth at their age. After raising three daughters, she wants a chance now just to be a couple again, to sell their house, to have a small apartment for two. He decides to seek a doctor for an abortion.

Danny is at the bus station, saying goodbye to Lizzie for his summer tour with the band.... Mr. Hart, a real estate broker, evaluates Alan and Arlene's home.... Nick and Pam are following the rules: no foreplay, no lubrication, one quick ejaculation and out ("Romance"). With his goodbye, Danny slips a ring onto Lizzie's finger ("I Chose Right"). Arlene announces to the realtor that the place is not for sale after all and that they'll need the extra space for the baby.

We see Lizzie at the mirror in her room, observing herself – obviously "in the family way." She stops, amazed, as she feels... "It moved!" Alone now, she sees that she has to face this on her own ("The Story Goes On").

Act Two

Mid-August. Lizzie, six-months pregnant and showing every moment of it, is confronted by women whom she meets on the street and who feel obligated to tell her about their own pregnancies, deliveries, and children — all in graphic detail that is rather off-putting for Lizzie ("The Ladies Singing Their Song").

Arlene, also six-months heavy with child, seriously looking inside herself, contemplates her life; expressing her fears, having her doubts, losing her nerve, but telling herself that she is fine ("Patterns").

Pam and Nick, in their bedroom, follow the doctor's instructions to the letter of the law, in between Nick reading passages from Moby Dick and Pam quoting rules and regulations from the fertility manual ("Romance –  Reprise"). The scene fades and comes up again on the pair. Now he's reading The Wizard of Oz. The regimentation is more than the pair can stand. They decide to abandon the procedures and both are relieved.

At the dinner table on their porch, Alan sits alone and contemplates how much simpler it is to love children than to love one's spouse. The demands between husbands and wives are so much more complicated because they see each other so clearly, whereas the children look upon their parents with admiration and a sense of awe ("Easier to Love").

The ensemble reflects on the season at hand, autumn.

The scene shifts to Lizzie and Danny's apartment, where he has just returned from his tour with the band. He empties his pockets, tossing bills and coins on the bed. She places his hand on her belly to allow him to feel the baby kick ("Two People in Love").

Alan and Arlene reassess their marriage, admitting their shortcomings — that they never indulged in extravagant expressions of love and emotion. Their love was always tempered with restraint. They are both astonished by their honesty and passion ("And What If We Had Loved Like That").

Lights come up on Danny and Lizzie. He is reading from a baby manual. Suddenly, she feels that she is going into labor. The birth. The nurses and doctor who are urging Lizzie to "push." The sound of a baby crying. Danny has witnessed the miracle and is in tears, overcome with emotion. Blackout, as a new generation begins.