Mary Mullen can't tell a joke, but she can sure make you laugh.

Three years ago, Ms. Mullen, a librarian at Bethel Park Public Library, became a certified Laughter Reader with the World Laughter Tour Inc., based in Columbus, Ohio.

"There's been a lot of research done to show how it really benefits us," Ms. Mullen said.

Laughter Clubs offer a place for people to come together to reduce their stress and improve their health by exercising with laughter, Ms. Mullen said.

"When you laugh, you take in a lot of air. It's very relaxing. It lowers blood pressure, increases blood flow and boosts the immune system," Ms. Mullen said.

What can visitors expect at the program, which is held at 11 a.m on the third Monday of each month at the library?

Not stand-up comedy.

"The basic philosophy of the Laughter Club is we don't use any jokes or comedy routines," Ms. Mullen said.

"We do laughter exercises. Because everyone's sense of humor is different, we don't want to wait for things that cause us to laugh. We create our own."

The meeting has two parts, the first deals with the physical aspects of laughter. Just like a regular exercise class, members begin with warm-ups including stretches and then some exercises to warm up their laughter. These exercises use the sounds of laughter and couple it with movement, motion or facial gestures.

"One exercise I do a lot with groups is called the 'Hawaiian greeting' exercise. I ask 'how do you say hello in Hawaii' and they respond 'aloha.' Then I say 'alo-ha ha ha ha' and we turn to each other, shake hands and repeat it to one another."

The length of time for each exercise varies. Another is called "ice cubes down the back." Members imagine they have a cold, wet ice cube in their hand and then they put it down the back of the person in front of them. "Each of us is trying to shake and wiggle this thing out. There's a lot of movement with it," she said.

The second part of the meeting focuses on what the Ms. Mullen calls "good-hearted living practices. There's one practice for each day of the week and a sixth for the weekends. Mondays are for compliments.

"We encourage people to look for the good in others, be less critical and judgmental," Ms. Mullen explained.

On Tuesday, members practice flexibility; Wednesdays, gratitude; Thursdays, kindness; and Fridays, forgiveness.

"Weekends are for chocolate. This lets people know it's OK to relax and give yourself a treat," Ms. Mullen said

She realizes that not everyone comes in ready to laugh.

"I tell people you don't have to be in the frame of mind to laugh when you come in. But by participating, it changes their attitude and makes them feel more optimistic and positive about life.

"Everyone has real problems and this doesn't take away the problems but gives them a way to deal with the difficulties in their lives. You can think of it as a coping mechanism perhaps," she said.

In addition to the Bethel club, Ms. Mullen takes the program to two area senior centers.

"It's for people of all ages. I do find the older adults are really responsive to it. Adolescents are a little more self-conscious and smaller children are very spontaneous. When something strikes them as funny, they just laugh and laugh. We aren't encouraging adults to be childish, but childlike," Ms. Mullen said.

The Laughter Club concept began in India under guidance of Dr. Madan Kataria. Steve Wilson, a psychologist from the United States, began the World Laughter Tour Inc. based on Dr. Kataria's clubs. The World Laughter Tour Web site, www.worldlaughtertour.org describes the program as "a worldwide movement for health, happiness and peace," and provides information on starting a club and becoming a certified Laughter Reader.

Ms. Mullen will also demonstrate the benefits of laughter tomorrow at Southminster Presbyterian Church's Adult Interest Center in Mt. Lebanon, 799 Washington Road. Lunch begins at noon for $6. For reservations, call 412-343-8900.