Five siblings gather at their father’s (Ron Crawford) deathbed.  This is a Catholic family with typically catholic politics.  Ann (Kathleen Chalfant) is the resident liberal atheist, and while she enjoys railing against the Church, she still takes the communion “to be sociable.”  Jim (David Chandler) and Michael (Keith Reddin), both physicians, are conservatives of the pull-yourself-up-by-your-own-bootstraps variety, though Michael is cosmopolitan enough to read Nicholas Kristof in The New York Times.  John (Daniel Jenkins), a college teacher, aligns himself with his brothers, while Wendy (Lisa Emery) just wants everybody to get along.

Sarah Ruhl’s For Peter Pan on her 70th birthday is part well-made play, part love letter to theatrical whimsy.  The title refers to Ms. Ruhl’s mother, who played the Boy Who Wouldn’t Grow Up as a child.  Divided into three “movements,” Peter Pan begins with a parent’s death, continues into an Irish wake, and concludes with its cast transfigured into J.M. Barrie’s characters.

The actors here are unusually strong and refreshingly unostentatious: this is an ensemble, and while there may be flashes of individual talent—Ms. Chalfant’s puckish verbal sparring, for example, or her incredible ability to mimic a crowing rooster—the real power comes from a collection of performers who are generous to one another.  At its best, Peter Pan captures the sound of a large family, a sound that is only authentic when it is not drowned out by a single voice.

Unfortunately, the text itself hardly demands such skill.  Ms. Ruhl claims she wanted “to write a play about one’s family without it being a ‘family drama’ of the sort that hinges on mudslinging and skeletons in the closet.”  Kudos.  This is the most boring gesture in American theater and she is right to be suspicious of it.  However, Peter Pan still reeks of that genre’s tropes: witty if overly artful dialogue, heavy drinking, fits of bittersweet nostalgia, and clunky final lines working far too hard to resonate after the blackout.  Though the third “movement” brings some life into the proceedings—actors whizz through the air and the audience “resurrects” Peter Pan through applause—it comes much too late, almost like an afterthought.  Peter Pen, then, is good enough to rise above the swamp of write-by-numbers American drama but far too unimaginative to realize its promise.

Furthermore, and perhaps more importantly, Ms. Ruhl fails to embrace the darkness of her central conceit.  What Peter Pan has to say about the terror of growing up, about Oedipal struggles, lost innocence, and looming mortality should provide rich material here.  These tragic elements were not lost on Barrie’s original children, who eventually outgrew and left him, with one recounting that he pretended to continue believing in fairies only to appease his older friend.  And yet Ms. Ruhl remains gratuitously optimistic: for her, childhood need never end and the theater a place where “my mother would live forever.”  On both counts, of course, she is dead wrong.

For Peter Pan on her 70th birthday runs through October 1st at Playwrights Horizons.  416 W. 42nd Street  New York, NY.  1 hour 30 minutes.  No intermission.