Six years and millions of dollars after its inception, a Fairfax County school program to increase achievement among disadvantaged students in some schools has yielded mixed results, and Superintendent Robert R. Spillane has called for a study of whether the program is worthwhile.

"Results have just been spotty over the years," said Rudolph Wiggins, director of minority achievement for Fairfax schools. "In some schools, there has been significant improvement in some areas, but it has not been to the school system's satisfaction."

At a time when the student bodies in the suburbs are rapidly becoming more diverse racially and economically, districts such as Fairfax find themselves increasingly faced with the issue of how to raise the achievement levels of students who are poor, may not speak English or have various other needs.

School systems tackle achievement problems with a multitude of programs, from magnet schools to reading initiatives to summer school.

In Fairfax, which has the area's largest school district, the cornerstone of the county's effort to help disadvantaged students since 1984 has been the so-called special-needs school program, which provides extra staff positions, money and resources to schools with high student turnover, low test scores and large numbers of poor, minority and foreign-born students.

Although the program is not aimed strictly at minority students, which in Fairfax include Asian, Hispanic and black students, it is one of the key ingredients of the county's efforts to improve minority achievement.

About a quarter of the county's 188 schools receive financing under the program, totaling about $8 million a year. Most of them are concentrated in communities such as Annandale, Seven Corners and Baileys Crossroads and along the Route 1 corridor.

At Bailey's Elementary School in Baileys Crossroads, Principal Carol Franz used her additional money to hire a liaison to work with parents of non-English-speaking children. At Dogwood Elementary School in Reston, Principal A. Prentice Christian Jr. created a reading laboratory where four or five students at a time can get individual instruction. At Cameron Elementary School south of Alexandria, Principal George F. Towery created a new computer laboratory.

"We think it helps a lot, especially when you have all the diversity and all the mobility we have," said Towery. "It puts us in the running with the other schools."

A school system analysis, however, provided both good and bad news about the effects of special-needs schools on minority students.

The good news: Fewer minority students are being held back in elementary and intermediate school, black and Asian students are receiving higher grades in intermediate school, and Hispanic and Asian students are increasingly enrolling in upper-level classes.

The bad news: Dropout rates among minorities have either gotten worse or not improved as much as rates at other schools, test scores have remained the same or declined for many minority students, and black and Hispanic high school students are being held back at a greater rate.

Noting the conflicting yardsticks, Spillane told the School Board last month that it was time to reconsider the program. "Are these approaches really working for our students?" he asked. "The evidence is ambiguous, and the tangible progress seems insufficient for the relatively long effort."

Robert E. Frye, the official minority representative on the School Board, who lobbied hard to start the special-needs program, said the concept is right but not enough resources are put into any one school.

"We get to say we have a special-needs program and we get to say it includes a lot of schools, but for a lot of them, it's just not enough to make that difference," he said.

As he sees it, the school system has two choices: Put a lot more money into the program, which seems unlikely given the county's current financial difficulties, or reduce the number of schools that receive the money so that it can be concentrated more in the neediest places.

Frye and others also complain that the best teachers seem to be assigned to schools that need them least. School system figures show that teachers in special-needs schools are less likely to receive merit pay bonuses than those in other schools.

Moreover, in rating teachers, the merit pay program does not measure student achievement, something Frye has been pushing Spillane to do for years.

For now, that and other issues remain under study. At Frye's suggestion, the school system hired former D.C. superintendent Floretta D. McKenzie last year to examine its minority achievement effort, and she is expected to report this spring.

NAACP President L. Marie Guillory, a vocal critic of Spillane, said she does not care how the school system raises minority achievement, as long as it produces results. "They need to get the most bang for the buck," she said.