JON CRISPIN PHOTOGRAPHY Robbie Simpson and Buzz Roddy in the New Century Theatre production of The Sisters Rosensweig .

This is Wendy Wasserstein Summer. The playwright's unexpected and untimely death last winter has inspired theaters across the country to mount memorial productions of her plays. Two of them are in this area. This week Northampton's New Century Theatre ends its season with The Sisters Rosensweig and next week The Heidi Chronicles opens at the Berkshire Theatre Festival in Stockbridge.

Wasserstein came of age in the '60s and '70s (she graduated from Mount Holyoke College in 1971), and her plays reflect the promises, challenges and disappointments of the Second Wave of feminism that (incompletely) liberated American women. Her most important contribution to the theater was putting interesting, complex women center stage and making their angst engaging by lacing it with humor. Her plays are wry but soft-centered portraits of successful, independent women, most of whom are Jewish and most of whose male friends are gay. Her characters are a lot like she was--smart, witty and quirky--but their hard-won sense of self-worth is nagged by self-doubt and the feeling that true fulfillment also requires true love.

The play's three sisters (and yes, there are a couple of winks at Chekhov) fit that mold in different ways and to differing degrees. Sara is a totally assimilated, twice-divorced executive of an international bank. Pfeni is a continent-hopping travel writer who wants to do serious journalism but has writer's block. And Gorgeous (a nickname that stuck) is a Newton housewife with a local-radio advice show and a fan base of middle-aged yentas.

The play unfolds over a couple of summer days in 1991, when an assortment of relatives, friends and friends of friends gather at Sara's London townhouse to celebrate her 54th birthday. Sara's daughter Tess (Alysondra Mila) and her Liverpudlian boyfriend (Robbie Simpson) are teenage firebrands ablaze with enthusiasm for Lithuanian independence. Pfeni (Celia Montgomery) has a sometime boyfriend, the genially amusing Geoffrey (Buzz Roddy), "an internationally renowned director and bisexual." His American friend Merv (Daren Kelly) is straight, Jewish and unrelentingly ebullient.

In this strong professional cast, I particularly enjoyed Stasack's coolly amused detachment as Sara, Roddy's relaxed aplomb as Geoffrey, and Mila and Simpson's hip naiveté as the young idealists. Director Ellen W. Kaplan moves things along at a nice clip, though the blocking, on Andy Stuart's sumptuous setting, often looks more like functional placement than natural movement.

Ironically, the show's most entertaining turn is also its biggest misjudgment. The character of Gorgeous is flamboyant and, as she says, "funsy," a self-mocking self-promoter who supplies a comic contrast to her sober sisters. Cheryl McMahon's performance is quite funny--the opening night audience didn't really come alive till she entered--but it's way out of keeping with the rest of the production. It's a complete shtick, a burlesque of New York Jewish speech and mannerisms that belong in a totally different play, not to mention a totally different family.

This indulgence skews the production. It flattens the other comic moments and exposes the holes in Wasserstein's script, in which most of the characters serve primarily as particular viewpoints or foils for the two other sisters' life-crises. With this tilt, the play that wants to be a bittersweet journey with the Three Sisters Rosensweig turns into Family Guest Day on the Dr. Gorgeous radio show.