There’s hardly a moment in the exhilarating, devastating revival of the musical “Falsettos” that doesn’t approach, or even achieve, perfection. This singular show, about an unorthodox family grappling with the complexities of, well, just being a family — unorthodox or otherwise — has been restored to life, some 25 years after it was first produced, with such vitality that it feels as fresh and startling as it did back in 1992.

The achievement seems almost miraculous, because in the intervening years, America has gone through cultural changes that might, in theory, have made the show, with its sweet-and-sour score by William Finn, and its economical book by Mr. Finn and James Lapine, seem a relic.

The musical, which opened on Thursday at the Walter Kerr Theater in a Lincoln Center Theater production, once again directed by Mr. Lapine — whose work is so sharp it’s as if he were seeing the show with a new pair of eyes — follows the topsy-turvy fortunes of a family of four, which eventually grows to five and maybe more.

At its center is the confused heart of Marvin (Christian Borle), a gay man in 1979 who introduces us in an early sequence to his lover, Whizzer (Andrew Rannells), and his ex-wife, Trina (Stephanie J. Block), along with Marvin and Trina’s precociously smart son, the 10-year-old Jason (Anthony Rosenthal). Although no one seems wholly at ease — rarely does anyone in this hilariously neurosis-infused musical — they have continued to maintain an equilibrium, to the point of still sharing meals together.