With just a few weeks of summer left, it's time for some serious lollygagging: lemonade and a chaise longue, with a thick, half-read novel nearby. A dip in cool, sparkling water would be lovely. And a charcoal-grilled cheeseburger always tastes better outside.

In short, all the ingredients for a great pool party.

Pool parties are one of the nicest ways to while away a summer day. Or they can turn out to be . . . well, all wet. Carol Maguire attended a pool party 14 years ago, and still remembers it vividly.

"It was an adult party," she says. "It was very well organized: They had music, they had the specialty drinks, a margarita man." The party started in the afternoon and continued into the evening. Maguire's date had too many margaritas, slipped on the wet poolside and cracked his head open--an injury that required many, many stitches.

"I ended the party at the emergency room," she says.

The Rockville mother of two was relaxing Monday, a picture-perfect summer day, at Rockville's Municipal Swim Center, a cool oasis with indoor and outdoor pools, water slides, shade umbrellas and fabulous curly fries. These are people who enjoy summer and swimming, and can recognize what makes a good pool party--or a bad one.

Take, for example, a recent Girl Scout get-together for 25 at a family backyard pool.

"It was a good party," Maguire says. "First of all, it was supervised by a lifeguard, so that made me feel good because I was able to socialize while my kids were in the pool. It was a potluck, which was a fun thing because everyone brought a little something. It made interesting conversation exchanging recipes. And no liquor--I don't think it's a good idea at a pool party because it's an obvious place for accidents."

Food, after the pool itself, is a critical ingredient of a memorable splash party.

"You need a way to keep yourself occupied if you're not in the pool, instead of staring at each other," says 19-year-old Ayda Nesvaderani. "A good pool party would have a barbecue."

"After the pool, everyone gets hungry," says her 15-year-old sister, Tara.

The combination of food and water temporarily transforms even the antsiest folks into calmer, more low-key individuals.

Beverly Donlan of Gaithersburg spent many days and nights at family pool parties at her sister's home. "We used to stay in the water until 10, 11 at night," she says. "If it was hot, you didn't want to get out. I think it's very relaxing."

But the mere existence of the pool and food does not guarantee a fun party. The next critical element is games: volleyball, beach balls, noodles, floats--anything that allows people to play in the pool.

"Just make sure going into the water is fun," says Ayda Nesvaderani. "Definitely have some kind of activity."

A good pool party has a certain amount of horseplay and splashing. Expect to get wet. A great children's pool party includes squirt guns or water balloons. A great adult pool party includes a few moments when grown-ups get to act like kids.

"My dad's best friend has a pool party every summer," says 20-year-old Farah Shirazi. "The guys get really drunk, take off their bathing suits in the water, and put them on their heads. The women all go into the kitchen. They're like, 'Oh, my God.' "

The stunt is an annual ritual, part of the party's tradition. Which brings us to the delicate question of displaying one's semi-naked body in public.

"Gotta have a bikini contest," says 18-year-old Charm Wright of Rockville.

"That's so sexist," says Shirazi.

Well, says Wright, the girls at the last party he attended showed off their well-tanned bodies. But no one should be cajoled or bullied into swimming or a swimsuit, even at a pool party. Some folks are just self-conscious. "I probably felt that way when I was younger, but after three kids it doesn't bother me," says Joyce Elliott of Gaithersburg.

Even men can be a bit nervous about parading around half-naked.

"From a guy's point of view, they care until they've had a couple of beers," says Eduardo Kenworthy, a volunteer firefighter in Rockville. "Then everyone has a washboard stomach."

And even at a casual affair, a thoughtful host remembers it's still a social occasion. That means introducing guests to each other, making sure everyone has enough to eat and drink, making everyone feel welcome.

"The problem with pool parties is that you can't please everyone," Kenworthy says. "It's like office parties or other social events: You have the same cliques that there are in the office, little clusters of people. Then you have the fun-and-games crowd, usually just an extension of high school, who throw shy people into the pool."

Kenworthy, who grew up in the Canary Islands off the coast of Spain, prefers the parties of his youth, where family members of all ages socialized together. "When you have more generations invited, there's more control," he says. "So you have a party that's fun for everyone."