Happy Now? National Theatre: Cottesloe, London

Having it all – it's what is expected of educated women nowadays, but it seldom lives up to expectations. It can leave a woman feeling as though she's simultaneously the rope in a multi-directional tug-of-war contest and the juggler hired to perform a fiendishly difficult balancing act.

This is not a new subject – there are novels, such as Allison Pearson's I Don't Know How She Does It, that have given the plight of the high-flyer working mum an amusing treatment. But Lucinda Coxon's wonderfully funny and painfully accurate play Happy Now? is the wisest, wittiest and most observant take on the topic so far. I found myself wincing with recognition and laughing out loud at the same time, in addition to feeling that odd sense of catharsis you get when someone has had the guts to go for broke and tell it exactly as it is. The piece is premiered now in the Cottesloe in Thea Sharrock's spot-on, superbly acted production.

Kitty (a pitch-perfect Olivia Williams) has two healthy young children; a demanding and worthy job as senior executive of a cancer charity; and a good-natured husband Johnny (Jonathan Cullen) who has recently switched career from lawyer to teacher in order to spend more time at home. Soon, however, Johnny is taking on extra responsibilities, such as "facilitating an inter-faith support group" after school, and their married life is lived in an atmosphere of exhaustion without fulfilment.

Coxon's comedy is sharp but never gloatingly superior as it takes us into the world of flung-together dinner parties and scrambles with the school lunch-boxes as bickering parents compete over who should win that morning's trophy for being most tired.

The astringency is heightened by the unravelling marriage of their friends – Miles (excellent Dominic Rowan), a witheringly cynical alcoholic who works in the legal firm Johnny has just left, and Bea (Emily Joyce), who bears the brunt of the breathtaking put-downs that represent Miles's compromise with his own self-hatred.

There's a terrific sequence that demonstrates the dramatist's alertness to contemporary sensitivities when Johnny, furious that the other couple are transferring their daughter from his melting-pot comprehensive to a faith school after a favourable assessment of her abilities, tells them straight out that their child is most certainly not gifted. It's a heady moment of heresy against the hypocrisies and self-deception of the middle classes.

Coxon's comedy hits nail after nail on the head. She's very good on the kind of intimacy women want from their friendships with gay men, such as Stuart McQuarrie's delightful Carl, and on the mutually exasperated relationship between thirtysomething daughters and mothers (like Anne Reid's hilariously irritating June) who are in constant rivalry (even, or especially, over illness) with the husbands who deserted them. Kitty is indignant that after all the careful stereotype-avoidance at home, her little girl is nonetheless a reincarnation of Ivana Trump. It's a nice truthful stroke when Reid produces a Sindy doll ("like Barbie but cheaper") that Kitty can't recall doting on and which she proceeds angrily to dismember.

The dramatist's most original coup, though, is the character Michael (played with powerful and expansive charm by Stanley Townsend). He's a fellow charity exec with whom she comes into contact in the latently louche setting of a mid-price hotel at the start and end of the drama.

Michael's chatting-up technique plays on the susceptibilities of women in Kitty's position. He understands the underlying dissatisfactions of the having-it-all way of life and he reckons that at some conference or other he's the man to create the "safe place where no one will judge you for lowering your standards just far enough to get what you really want. Really need."

Is this guy the answer to a secret prayer or a multiple-bluff operator? The surprising development of that strand is a sign of the emotional maturity and honesty of Coxon's first-rate play for today.

To 15 March (020-7452 3000)