TWENTY-FIVE SUMMERS ago, Joe Gallagher tried to start one of the area's first specialized sports camps.

"Let's say it did not work out as well as I planned," says Gallagher, the veteran athletic director and basketball coach at St. John's High School. "By the end of the summer, I was trying to sell real estate."

Gallagher's inability to fill his initial basketball-football camp didn't dampen his conviction that youngsters eight and older would like to spend a summer week or two learning their favorite sport rather than attending the traditional varied-activity day camp. So the following summer he teamed with DeMatha Coach Morgan Wootten to form one of the area's longest-running, and most successful, summer basketball camps.

After them came the flood. "Now, every kid wants to go" to specialty sports camps, "and every coach in high school or college is running one," says Gallagher.

Although the final sessions ofhis and a number of other specialized camps are over for the summer, many other camps are still accepting youngsters for training in such sports as basketball, field hockey, football, lacrosse, soccer, tennis, track and volleyball.

Most camps have instruction for youngsters eight through 17. (Recent high school graduates are ineligible regardless of age because of National Collegiate Athletic Association rules.) In general, one-third to one-half of the sports camping population is composed of youngsters 12-and-under.

Few camps discourage applicants, but organizers emphasize that their camps are structured for youngsters who want to learn more about a sport. They say their camps are not general day camps or simple playgrounds and should not be used as outdoors babysitters.

Staff "counselors" usually are high school or college athletes, and several camps will bring in big-name coaches or athletes to lecture.

For junior and senior high school athletes, camps provide a chance to sharpen skills and advance the players' strategic approach to a sport. But most camps also cater to youngsters with minimal experience, or those who have never played and want to learn.

"The younger they are, the less lecture we give," says American University soccer Coach Pete Mehlert, who is in his 12th summer of running a camp. "We want to hold their interest," he says, so his camp offers "small-sided games," with abbreviated time limits and just a few players to a side. That way, he says, "we can immediately put into practice what we teach them."

Woodward High School soccer coach Dave Scaggs, who runs a camp at the Bullis School in Potomac, feels a loose atmosphere is the key to keeping youngsters interested. One morning each of his staff members will conduct heading and trapping drills wearing the most unusual hat they can find. On another day, he'll have the instructors dressed in outlandish clothes.

"We have two objectives," says Scaggs. "The first, by far, is to have fun; the other is to learn. For younger kids, we really are entertaining all day, but simply, you can teach twice as much if the kids are having fun and are relaxed."

The approach does vary camp-by-camp. Some camps try to accomplish maximum teaching in daily sessions of two hours. At the other end of the spectrum are places like the Navy basketball camp, directed by new coach Pete Herrmann, where commuting campers (overnight accommodations are also available) are on the Annapolis campus from 8:30 a.m. to 8:45 p.m. for each of the five days.

Costs can range from the $35 charged for five two-hour sessions at the Sue Tyler Field Hockey Camp at the University of Maryland to $264 for the seven-day sleepover camps run by Terrapins basketball coach Lefty Driesell.

Parents and youngsters tend to view the camps as more than a week of summer fun.

"We send them to these camps to improve their skills; it helps them all year," says Sandy Goepfert of Potomac, whose sons Rick, 16, and Jimmy, 14, have attended the Bullis soccer camp for eight years each. "There is no time during the year they can learn as much as they can in the summer."

For colleges and private high schools, the camps provide an additional benefit beyond pure profit: They can be a wonderful showcase and recruiting tool for the institution. And if some youngsters show promise of becoming athletic stars, the coach can have an immediate edge.

"There is no doubt that is a small factor in running a camp, but it is very true," says Belinda (Boe) Pearman, who has worked seven years at the camp of Maryland women's basketball coach Chris Weller. "Our staff spends a lot of time with the kids. Some write to me for years. Christy Winters Washington area girls high school player of the year this past year of South Lakes came to our camp for years. She loved Maryland, learned the system and we just signed her." SPORTS OF ALL SORTS

The following are among the specialized sports camps still accepting youngsters for summer sessions: BASKETBALL BULLIS CAMP -- At the Bullis School, July 28-Aug. 1 (boys); Aug. 4-8 (girls), 9 a.m.-3 p.m. daily. $80. Ages 9-14. Call 926-6074. LEFTY DRIESELL'S CAMP FOR BOYS -- At the University of Maryland, Sunday through July 26. Overnight only, fee $264. Ages 8-18. Call 454-2126 (There is a waiting list already, but organizers say cancellations occasionally provide more openings.) CHRIS WELLER'S CAMP FOR GIRLS -- At the University of Maryland, July 27-Aug. 1. Overnight fee $235; day camp from 9 a.m. to 4 p.m. $120. Aug. 10-15 $120 (day camp only). Ages 9-18. Call 454-2483. GEORGETOWN U GIRLS CAMP -- July 27-Aug. 1. Overnight fee $235; day camp only, 8:30 a.m.-4 p.m., $150. Ages 8-17. Call 625-3504. NAVY CAMP -- Sunday through July 25 (boys); Aug. 3-8 (girls). Overnight fee $185; day camp 8:30 a.m.-8:45 p.m. $130. Ages 8-17. Call 301/267-3685. ST. ALBAN'S SCHOOL SUMMER PROGRAM -- Monday through Aug. 1. $150 for two-week session, 1-4 p.m. daily. Boys and girls ages 10-15. Call 537-6450. SCREAMING EAGLE CAMP -- At Seneca Valley High School, Monday through July 25 (girls); July 28-Aug. 1 (boys). 8 a.m.-4 p.m. $75. Ages 8-16. Call 926-2453 (days); 258-7413 (evenings). FIELD HOCKEY SUE TYLER CAMP -- At the University of Maryland, Aug. 3-8. Daily sessions 9:30 a.m.-3 p.m., $70. Nightly sessions 6:15-8:30 p.m., $35. Girls 12-17. Call 454-5854. FOOTBALL GAME PLAN CAMP -- At Churchill High School, July 28-Aug. 1 (beginners 10-18) and Aug. 4-8 (players 14-18 with varsity experience only), 4-7 p.m. daily. $75 each session. Call 774-6716. LACROSSE DICK EDELL CAMP -- At the University of Maryland, July 27-31. Overnight fee $215; day camp only, 9 a.m.-9 p.m., $75. Boys 10-17. Call 454-4328 or 442-5585. SOCCER AMERICAN U CAMP -- July 28-Aug. 1, Aug. 4-8, Aug. 11-15. 9 a.m.-5 p.m. daily. $135 for one session, $250 for two, $350 for three. Boys and girls 7-18. Call 885-3014 or 885-3020. NAVY CAMP -- Monday through July 25, 9 a.m.-8 p.m. daily. $160. Boys 8-18. Call 301-267-3153. ST. ALBAN'S SCHOOL SUMMER PROGRAM -- Monday through July 25. 9 a.m.-noon daily for boys and girls 5-12, $75; 9 a.m.-3 p.m., $100. July 28-Aug. 1, 1-4 p.m. daily for boys and girls 12-17, $75. Call 537-6450. ALDEN SHATTUCK CAMP -- At the University of Maryland, Sunday through July 24. Overnight fee $195; day camp, 9:15 a.m.-9 p.m., $130. Boys and girls 6-18. Call 454-5854 or 454-6907. TEAM MONTGOMERY CAMP -- At Bullis, Monday through July 25. 9 a.m.-3:30 p.m. daily. $95. For advanced boys and girls born in 1972, 1973 and 1974. Call 924-2110. TENNIS GEORGETOWN U CAMP -- Monday through July 25, July 28-Aug. 1, Aug. 4-8. 9 a.m.-4 p.m. daily. $150 each session. Boys and girls 17 and under. Call 625-3504. ST. ALBAN'S SCHOOL SUMMER PROGRAM -- Monday through Aug. 1. Separate sessions daily from 8:30 a.m.-10:30 a.m., 10:45 a.m.-12:45 p.m., 1 p.m.-3. $155 for each two-hour-daily, two-week session. Boys and girls 8-15. Call 537-6450. TRACK JOHN COOK TRACK AND FIELD CAMP -- At George Mason University, Monday through July 25, 8:30 a.m.-noon daily. $35. Boys and girls 8-18. Call 323-3872 or 425-8299. CAMP VARSITY -- In Madison, Va., about 1 1/2 hours from D.C. Aug. 3-9. Overnight only, $150. Boys and girls 13-18. Call 323-3872 or 425-8299. VOLLEYBALL BARBARA DRUM VOLLEYBALL CAMP -- At the University of Maryland, Aug. 11-15, 9 a.m.-4 p.m. daily. $75. Boys and girls 12-17. Call 454-5854. GEORGE MASON UNIVERSITY CAMP -- At George Mason, July 28-Aug. 1, 5:30-9 p.m. daily. $55. Boys and girls 12-18. Call 323-3043. GEORGE WASHINGTON UNIVERSITY CAMP -- Aug. 9 (9:30 a.m.-5 p.m.) and 10 (10 a.m.-1 p.m.) for setters only. $35. Aug. 10-14 general skills, 9:30 a.m.-5 p.m. daily. $130. Boys and girls 8-18. Call 676-6152.

Neil H. Greenberger last wrote for Weekend on doll shows.