THEATER HAS ALWAYS responded immediately to its surroundings, "acting out" as soon as personal and social issues arise. The dramatic action is most often seen on the page and stage. But sometimes the theater gets involved in Good Causes in a more hands-on way:

SHAKESPEARE THEATRE artistic director Michael Kahn, who spoke out against the gathering threat of arts censorship at the sixth annual Helen Hayes Awards, is a man true to his word. In his remarks, Kahn urged theaters and audiences to mobilize for the reauthorization of the National Endowment for the Arts, in spite of "end-of-the-season fatigue." Kahn has had an advocacy/action booth set up in the theater lobby during performances of his hit staging of "The Merry Wives of Windsor," featuring posters explaining the issue at hand and the freedoms at stake, and a supply of printed postcards. They say, "I support the President's proposal to maintain full NEA funding without content restrictions. As a member of your constituency, I urge you to stand behind reauthorization for the NEA with no strings attached. Censorship is not the American way."

Shakespeare Theatre representatives will hand-deliver signed postcards to the Hill offices of local politicians, including Steny Hoyer, Connie Morella (both D-Md.), Stan Parris (R-Va.) and Walter Fauntroy (D-D.C.). "Merry Wives" has been extended through July 1.

LONG BEFORE television and movies got the picture about the severity and scope of the AIDS crisis, playwrights were on the scene, urging awareness and action through works like "The Normal Heart" and "The AIDS Show." Theatre Communications Group has just published "The Way We Live Now," a collection of 10 plays inspired by the AIDS crisis.

Four of the plays have been produced on Washington stages: Studio Theatre produced William Hoffman's "As Is," one of the first theatrical responses to AIDS. Source Theatre did Harvey Fierstein's "Safe Sex" and turned the Broadway flop into a long-running 14th Street hit; one act of the play is reprinted here, along with the playwright's note: "Never lose your sense of humor." Studio Theatre currently has a hit with its production of Durang's "Laughing Wild," and the male character's monologue reprinted here includes material Studio cut from its version. And Woolly Mammoth recently closed its production of Harry Kondoleon's "Zero Positive," which closes the book.

The anthology, which features one of Robert Mapplethorpe's calla lily photographs on its cover, takes its title from a short story by Susan Sontag. First published in the New Yorker, the story consists of the voices of 26 friends (one for each letter of the alphabet) discussing a friend's unnamed illness; it was arranged for the stage by Edward Parone, who calls it "a punctuator's nightmare." Rounding out the anthology are Lanford Wilson's grim monologue "A Poster of the Cosmos"; a scene about Roy Cohn from Tony Kushner's fantasia "Angels in America"; Paula Vogel's short one-act "The Baltimore Waltz"; David Greenspan's choral poem-play "Jack"; and "Andre's Mother," in its original form as a two-page vignette -- it was later expanded for the PBS "American Playhouse" series.

Village Voice critic and translator Michael Feingold wrote an intelligent and sensitive introduction, which begins by comparing the AIDS crisis to a play with an invisible protagonist, a villain which causes unimaginable world-scale suffering while never showing its face onstage. Feingold also addresses the would-be censors of plays like "The Normal Heart" (not included in the volume at playwright Larry Kramer's request) who would "rather protect their ears than their grandchildren," and posits plays as models of behavior in crisis.

ALTRUISM IS alive and well, on stage at least. The Shakespeare Theatre is adding a performance of "Merry Wives" June 10, with net box office proceeds earmarked to benefit Art Against AIDS. The actors are donating their performances. Call 546-4000. Proceeds from Monday's performance of "Joseph and the Amazing Technicolor Dreamcoat," an early Andrew Lloyd Webber rock musical at the West End Dinner Theatre, are also headed for Art Against AIDS. Call 370-2500.

And cast members from the Lloyd Webber musical "Starlight Express" flew in from Miami last week for a benefit performance for the D.C. Hotline, the city's only comprehensive telephone counseling and crisis intervention service. After the "Starlight" troupe finished its Sunday matinee in Miami, cast members hustled to the airport, arrived at the Citadel Center at 9:30 p.m., and hung up their locomotive-inspired costumes to air out. They rehearsed a special staging of five numbers of the show, complete with roller-skating choreography, performed it Monday at the Citadel, then flew back Tuesday to make an 8 p.m. Miami performance. About 500 attended the benefit, including the cast of "Cats," which was playing the National Theatre -- many of the "Cats" and "Starlighters" have cavorted in both musicals.

"The show is about the triumph of good, and we want to be associated with good causes," said company manager Robert Nolan. "Starlight" rolls into the Kennedy Center Opera House June 12-July 15. Call 467-4600.