Paul Donnelly started writing plays partly because he was not getting very far acting in them. Now 28 and facing the opening this week of his first produced play, "After My Own Heart" at the New Playwrights' Theatre, he remembers a disastrous audition as the impetus for his change of focus.

He was auditioning for NPT, as fate would have it, and prepared a bit of "You're a Good Man, Charlie Brown" for his first piece. "The speech called for a peanut butter sandwich, so of course I brought one for a prop." But he took too big a bite, it stuck to his mouth, and "I spoke Portuguese." To make matters worse, he was to follow this "comic" speech with a serious one -- which happened to be about a homosexual rape -- and saw no way to rid himself of the wretched mouthful other than to spit it into his hand and hold it. "Everyone watching was hysterical, but I found the experience rather painful," he says.

But Donnelly, a graduate of Bishop Ireton High School and the University of Virginia, went on to take play-writing courses at NPT and, in fact, now teaches one. If he's learned anything, he says, it's this: Don't write the dialogue first -- do the groundwork, an outline of the story, biographies of the characters, whatever it takes. "It's easy to write page after page of aimless dialogue," he says.

"After My Own Heart" is a comedy about a 32-year-old woman who lives with one man but is married to another. When her husband reenters her life she is forced to make a choice. The idea for the play, Donnelly says, grew out of two things. The first was hearing a friend, who had decided with her husband not to have children, talk about the hassling she got from friends and family about that decision. As often happens with rehearsals, that theme has become a minor part of the play.

The second was seeing the Elizabeth Taylor-Richard Burton production of Noel Coward's "Private Lives." "She was embarrassing and he was beyond the pale," Donnelly says. "But it made me reread the play. The dialogue is very witty, but there's no tension because it's obvious that Amanda and Victor are made for each other and their new spouses are simps. So I thought about giving a woman a choice between two equally attractive men, and what that would set up."

The rehearsal process has been a new experience. The play is being directed by NPT artistic director Arthur Bartow, who, he says, has a "velvet fist" -- "he gets you to go in a direction you had no intention of going in, and you don't even realize it."

Of course, writing plays doesn't pay the bills yet, so during the day Donnelly works for AT&T, designing circuit layouts for corporate phone systems. But his coworkers know about his other life, and he hopes some of them will come to see the show.