“The Great Work begins.” When we first heard the Angel of America bellow that bulletin as the curtain came down on Part 1 of the play named for her and her band of anxious immortals, many of us who look to the theater for inspiration were, in fact, inspired. Tony Kushner’s “gay fantasia,” fusing the ambition, morality and underdog sympathies of earlier 20th century masters, felt not only like a great American play but like a culmination and reimagining of great American playness. It slammed a door open.

That was 1993. Exactly 25 years later, the first Broadway revival of “Angels in America” started us thinking about what has happened to American plays in the meantime. Have they been as great? Is their greatness different from what it was? Is “greatness” even a meaningful category anymore?

Perhaps not on Broadway. Of the plays we’ve singled out as the best 25 of the last 25 years — dated by their first reviews in The New York Times — only nine have ever appeared on Broadway, and none originated there. No matter their size, most began on, and many never left, the smaller stages of Off and Off Off Broadway, or were developed at regional theaters.

If they have reached fewer people as a consequence, they have told more stories: the kind often ignored during the decades when theater was still a dominant but homogeneous cultural force.

The most obvious and hopeful evidence of that change is the diversity of playwrights and subjects represented on our list. The diversity is only natural because the most exciting theater is often (not always!) about the most urgent issues in the world it reflects. Works exploring race and gender are prominent, for instance, because racism and sexism remain prominent.

Not that we aimed for that result; in fact, our list — which includes only “straight” plays, not musicals — was put together using such a complicated and secret method that even we don’t understand it. Nor is our grudging ranking of the 25 any less arbitrary just because it emerged from a reasoned debate.

What we do know is that the critics Laura Collins-Hughes, Alexis Soloski and Elisabeth Vincentelli joined us, The Times’s chief theater critics, in a series of round-robin ballots, Faustian horse trades and attempts at persuasion, sometimes successful.

Still, you may feel, as we eventually did, excited enough by the 25 plays to want to reread all of them, catch their next revivals or check out those that have been made into films. Taken together, they constitute a fairly representative — and optimistic — snapshot of the best (mostly mainstream) theater in America since 1993.

It’s a theater that is often more directly engaged in unpacking large-scale social issues than we at first expected. But it’s also a collection marked by imaginative boldness that would not surprise that interloping angel who delivered the millennial challenge 25 years ago. Let the Great Work continue!