At St. Anselm's Abbey, a small private school for boys in Northeast Washington, half of the 28 seniors have qualified as semifinalists in this year's National Merit Scholarship competition.

Walt Whitman High in Bethesda, a perennial high producer in the contest, has 34 semifinalists, giving it the sixth-highest total among the 19,000 schools whose students participated nationwide.

T.C. Williams High School in Alexandria and Sidwell Friends, a private school in Northwest Washington, tied for second in the Washington area with 18 semifinalists apiece.

By contrast, the 14 D.C. public high schools have four semifinalists in the competition, down from eight a year ago. The 20 public high schools in Prince George's have 14 semifinalists, nine at one school, Eleanor Roosevelt.

The results, released yesterday by the National Merit Scholarship Corp., are a widely used measure of exceptionally strong students and where they go to school, although the group that sponsors the competition discourages comparisons between schools and school systems. {Lists of the individual semifinalists appear in the Weekly sections of The Washington Post today.}

"The fluctuations year-to-year don't mean very much," said John F. Keating, guidance director at Walt Whitman. "But over time {the results} are significant . . . . If we dropped off the cliff for a number of years, there would really be some soul-searching here."

Janis Cromer, a spokeswoman for D.C. School Superintendent Floretta D. McKenzie, noted that "the numbers {of Merit semifinalists} change from year to year," and added, "We're always proud of the ones we do have."

The area schools with the largest number of semifinalists this year include Holton Arms in Bethesda and St. Albans in Northwest D.C., each with 16 apiece; St. Anselm's and W.T. Woodson, a Fairfax public school, 14 apiece; McLean High in Fairfax, 13; and Bethesda-Chevy Chase High in Montgomery, 12.

All of them are either selective private schools or public senior highs drawing substantial numbers of students from affluent, college-educated families. But T.C. Williams, which serves the entire city of Alexandria, is the most diverse senior high in the Washington area.

"We have the most affluent and we have the ghetto too," said James E. McClure, the school's guidance director. "It can work, but you have to work at it. There's something here for everyone."

Overall, Fairfax has the most merit semifinalists, 150; followed by Montgomery, 113, and D.C. private schools, 68. Many of the semifinalists at District private schools live in the suburbs, particularly Montgomery County. At St. Albans, seven of the 16 live in Maryland, as do eight of the 14 semifinalists at St. Anselm's, which has by far the highest proportion of Merit scholars among its students.

Among area school systems, Alexandria has the highest proportion of students qualifying as semifinalists -- 2 percent -- followed closely by Falls Church, Howard, Montgomery, Arlington, and Fairfax counties -- all between 1.8 and 1.3 percent.

Of the four semifinalists in D.C. public schools, two attend Wilson High in Northwest. The two others are twin sisters, Carrie and Laura Dove, who were students last fall at the U.S. Senate Page School, operated by the D.C. public school system. Previously, they attended Sidwell Friends for two years.

The Merit semifinalists were picked on the basis of a 100-minute multiple-choice test in English and mathematics, given last October to about 1 million high school juniors. About 15,500 were selected as semifinalists. Next spring about 6,000 will be awarded Merit scholarships for college.

Although all students took the same test, the number of semifinalists for each state is proportional to the size of its high school graduating class. Thus, the score needed to qualify varies -- 205 this year in Maryland and the District (out of a possible 240 points) and 203 in Virginia.

The North Carolina School of Science and Mathematics, a statewide public boarding school, had the largest number of semifinalists in the country, 77, but the qualifying score in North Carolina is low at 192.