"One day I'm gonna put all of this in a book or a play," threatens young Eugene Morris Jerome, bearer of "the second worst name ever given to a male child" (the first being "Haskell Fleischmann").

Brainy beanpole Eugene -- ignored, excitable and keenly observant youngest son of a beleaguered Jewish family in 1937 Brooklyn -- is the autobiographical alter ego of playwright Neil Simon in the nostalgic comedy "Brighton Beach Memoirs" at the National Theater.

There have always been those who sneer automatically at each effort by the prolific and profit-making playwright. And while it's true that parts of this play sound as if they were transcribed directly from his boyhood diary, it can't be denied that Simon has a gift for sketching America in small-scale situations.

"Memoirs," which stresses home truths as much as humor, is an idealized representation of Simon's own childhood in which people have problems, hurt each other, make up, and Learn a Lesson. Simon precipitates an avalanche of major and minor crises that loom large in the minds and hearts of the Jeromes.

There's a lot of life under this one roof: restless older brother Stanley; omniscient mother Kate; overworked and worried dad Jacob; and widowed Aunt Blanche and her two daughters -- Nora, a budding chorine, and pampered, asthmatic Laurie. Simon never allows the characters to slip into stereotype, and the cast obliges him with the look and feel of a real family.

And then there's Eugene, ingratiatingly played by Patrick Dempsey, a fidgety ball of adolescent energy, with a cartoon face and eyebrows, ears and hair that move of their own free will.

While the rest of the world teeters on the brink of World War II, Eugene totters on the edge of puberty. He plans to become a writer if things don't pan out wh the Yankees, and the travails of the Jerome family provide his diary with reams of raw material.

Though there are plenty of laughs, Simon avoids the glib, tenderly probing the often-awkward moments where confused emotions cause unconscious hurts. When he sticks close to home, as he does in "Memoirs," Simon's at his best, finding the natural wit, wisecracking and hyperbole in the words and wisdom of everyday people. BRIGHTON BEACH MEMOIRS -- At the National Theater through January 6.