The Springbrook High School class of 1966 wants blue balloons, 20-year-old hits such as "Ballad of the Green Berets" and "I'm a Believer," and an updated yearbook with the current addresses of the 526 class members. But most of all, when the night arrives in April for their 20-year reunion, alumni of the Silver Spring high school want a big turnout.

All that is not easily done, class members said. It took two of them nearly a year to arrange the 10th reunion. But this time they have hired a Rockville firm called the Reunion Co. to do it all.

The company, run by Betsy Flaherty and Pat Kogod Hughes, has organized six large reunions since it was founded last June. Plans are under way for planning 37 others, including the Springbrook event, which will be held at the Sheraton Potomac Inn in Rockville.

Flaherty and Hughes, who say they are the only reunion organizers in the area, do everything: They find a site, hire a caterer, track down alumni, print and mail invitations, produce an updated yearbook, register the guests and supervise the party.

A spirited duo who tend to complete each other's sentences, Flaherty and Hughes said their immersion in the planning is necessary if the reunions are to be a success.

"We're here to take the worry away from the class," Hughes said. "You can't have a good time if you're worrying if the coffee is hot on table 9," added Flaherty.

Hughes, 36, and Flaherty, 43, said the key to a successful reunion is having as many people as possible attend.

"Turnout is everything," said Flaherty. "People forget about where it was, or what they ate. What they remember is who they saw and how many people were there."

"And who looked good," Hughes added.

Judy Kornhauser Portas, who helped coordinate the 10th reunion for the Springbrook class of '66, says it is a relief to have "the bulk of the responsibility" taken care of by pros.

The biggest surprise, said classmate Nancy Mercogliano Yates, has been "that they found so many people. We already have more people signed up now than came to the last one."

To find long-gone alumni, the company has nine part-time researchers, who work out of their homes and are paid on commission, Flaherty said.

Researchers track down a surprisingly high percentage of alumni by calling parents, siblings and friends; sending announcements to radio stations, newspapers and magazines, and using lists provided by colleges, professional groups and the military, she said. Even with classes of 700, they have been able to find up to 90 percent of the graduates for 10-year reunions and 75 to 80 percent for 20-year events, she said.

While they have located alumni of local high schools in places as far away as Saudi Arabia and Spain, Hughes said they find the vast majority in the Washington area, belying the reputation of Washington as transient city.

"If they are not here, their parents are, or their brothers or sisters," added Flaherty. "There is almost always a way of finding them."

Ticket prices for the reunions range from $20 to $40 per person, Hughes said. Four dollars of the fee is a service charge for the company, and the rest is for reunion expenses.

The company has an arrangement with radio station WXTR-FM, Hughes said. The "oldies" station sends disc jockeys to play the hit records of the class' school days, and Reunion Co. employes wear the radio station's badges and hats at the event.

The station does not charge for its services because "they get a lot of good will out of it," Hughes said. "The classes love it. Of all things a reunion is, it's nostalgic and corny, and music is very important. It brings back a lot of good memories."

Ken Cudd, who hired the company to handle a reunion last November for the Northwood High School class of 1980, said it turned out better than he had hoped.

They had anticipated having 190 people show up, he said, "but in the last three days, we got swamped with responses, and ended up with over 230."

The organizers "picked up the extra 40 people with no problem, and everybody had a great time," he said. "I was surprised at how smooth it went off."