“I don’t think that any play shouldn’t be funny,” said actress Deirdre O’Connell. “I can’t imagine being happy if I was in something that wasn’t funny at all. That doesn’t mean that I like comedy. I just, I can’t think how something works where something funny doesn’t happen.”

It’s a pretty amusing comment from a performer whose last off-Broadway credit was Neal Bell’s “Spatter Pattern (Or, How I Got Away With It),” about a screenwriter who becomes involved in the life of a professor being investigated for murder, and whose next project, “Pyretown” (which begins performances off-Broadway today) is about a love affair between a wheelchair-bound young man and a middle-aged single mom.

But, then, Ms. O’Connell looks like a gal who’s had a lot of fun, or at least tried damn hard to. The wavy brown hair is abundant and unkempt, the eyes large and smiling, the mouth wide and loose. She laughs a lot but doesn’t always seem to know why she’s laughing. The general aura speaks of a slightly punch-drunk party girl. Just the sort who would drive her educator dad crazy by pulling down bad grades and skipping the prom.

Which she did. “It was the one thing I could do that would really mess with him!” she laughed. “Poor guy!”

Certainly, she has brought theatergoers and critics their share of good times. Since hitting the Gotham scene in the 1980s, she has delivered dozens of quirky and praised performances that seem simultaneously spot-on and tossed off. If an actor can be specific and spontaneous at the same time, it’s Ms. O’Connell.

“I think Didi is one of the most exciting, interesting actresses around,” said director David Esbjornson, who worked with her on Suzan-Lori Parks’s searing urban drama “In the Blood” at the Public Theater and “Mud” at the Signature Theatre Company. “She has this amazing ability to make the audience connect with her. At the same time, she is eccentric and ethereal.”

There’s always been something of the peculiar in Ms. O’Connell’s stage presence. “Often, in my early days, I played people that were very idiosyncratic. A crazy nun in ‘Agnes of God.’ Nutty teenagers and people with brain damage. What do you do with a girl like that?”

“I think that’s a part of who Didi is,” argued Mr. Esbjornson. “That’s her way of being truthful. She can take things in a straighter direction, but I don’t think that’s who she is, so there’s always an eccentricity that comes through in her role. That’s a reason to cast her. It doesn’t make any sense to make her any duller than she is.”

Mr. Esbjornson retains a telling memory of directing Ms. O’Connell in “In the Blood,” where the actress played both a bedraggled hooker and the child of a homeless woman. “Her major monologue was as the prostitute,” remembered the director. But she played the tot first, so “in order to warm up on the stage before a show she had to be dressed as the little girl. I have this image of her saying all of these foul, rather rude things, while in a little party dress.”

Ms. O’Connell was raised in Pittsfield, Mass., where her father founded the Berkshire Community College. Unhappy at school, she gravitated toward the college’s play rehearsals. “I think it’s true of a lot of actors,” she said. “I think there’s some weird thing that happens where you’re uncomfortable in your life and you’re shy and you don’t fit in. It’s such a common story. Then you’re at the Pittsfield Girls Drama Club when you’re 8 and there you feel really comfortable, and that you are pretty, for whatever reason. You find your compadres, and you feel simpatico. Then you move to New York to be with your fellow drama-club nerds.”

Before New York, though, there were a few years in Boston, where she worked with a Growtoski-based experimental troupe called Stage One. Early New York credits included “The Front Page” at Lincoln Center (her sole Broadway credit) and several outings with the Women’s Project, including “Approximating Mother.”

Her rise was interrupted a decade ago by a years-long sojourn in Los Angeles, which was born when “I looked around and said ‘Oh, my God, I don’t have any money at all.'” She returned to New York in the late 1990s after witnessing the work of a few fellow character actresses, including J. Smith-Cameron and Kristine Nielsen.

“I saw them in different things, and I had no idea how they did it. There was something that had happened to their chops, just by having done theater all those years. I said, ‘I have to return and get that back. I really didn’t know if anyone would remember me. They would be all new people casting the plays and running the theaters. Even in five years, it changes so fast.”

Now comes the point in the story where the journalist tells of the artist’s career-changing Big Break. But Ms. O’Connell’s tale doesn’t fit that boilerplate. “I don’t think I’ve had a big break!” she exclaimed, apparently recognizing the fact for the first time. “There are some things that happen to people that are pretty concrete. I feel like it’s been so gradual that there’s never been a perceptible bump.”

“Pyretown” might provide that bump. For one thing, it represents a relative rarity on Ms. O’Connell’s resume: a leading role. The text grabbed her from the moment she read it. “The script was really beautiful. I was immediately attracted to it. You don’t have that feeling very often. It’s a love story. There haven’t been a lot of love stories that I’ve done.

“It’s interesting, because from the very beginning of rehearsal, they were taking for granted that my character was a total babe that any man would be falling over himself for. I don’t see myself that way. But, I’m like, ‘Yup! That’s me all right!’ And it’s really fun, because they’re buying it. It’s kind of great!”

Ms. O’Connell recently used the money she gathered in Los Angeles to buy a country home in upstate Kinderhook, after first convincing her longtime boyfriend to move back East. So she expects to spend the rest of her career in New York – a bit of good news for casting director and ticket buyers.

“What you look for at a certain point is to just be very happy at work,” she theorized. “When you’re young, there are fantastic parts that come your way. And then there’s this dead area in the middle where you’re a really nice mom or a really nice love interest. And now there seems to be another great period. If you keep going, it’s a real pleasure that’s worth staying around for.”

“Pyretown” (Urban Stages, 259 W. 30th Street, between Seventh and Eighth Avenues, 212-868-4444).