Bilingual education, once widely hailed as a humane and sound method of immigrant assimilation, has fallen into disfavor, disparaged as a bureaucratic boon-doggle, even by many of the people it was primarily designed to serve: the nation's increasing Hispanic minority.

On Tuesday, California voters are expected to endorse Proposition 227, which will eliminate the hundreds of bilingual programs in a state that is home to nearly half of the pupils in the United States of limited English proficiency, setting the stage for similar attacks on such programs nationwide.If it passes, Proposition 227, which essentially limits help to non-native speakers to a year of intensive English instruction, will mark an extraordinary intervention by voters into classrooms to mandate teaching methods, a sign of the growing importance of edu-ca-tion in the nation's political debate.

The shift in the fortunes of the nation's bilingual education system has been dramatic, the result of flagging support among its key constituents, Hispanics; a growing political resistance to federal education bureaucracies; and the sense that, despite a plethora of studies, there was no conclusive evidence that it worked.

Behind that erosion of support is a stubborn statistic: the high dropout rate of Hispanic youths.

According to the National Center for Educational Statistics, the school dropout rate in 1995 of Hispanics ages 18-24 who were born in the United States remained at 17.9 percent, but that of Hispanic immigrants was 46.2 percent. This compares with 12.2 percent of blacks and 8.6 percent of whites who drop out. Foreign-born blacks and whites had lower drop-out rates than those who were born in the United States.

Since three-quarters of schoolchildren nationwide who speak limited English are Hispanic, and since bilingual education is often made to stand for the whole question of educating foreign-language children, the failure of the schools to educate Hispanic youths is often discussed interchangeably with bilingual education as if they were the same thing.

While the initiative is the work of a white Republican Silicon Valley millionaire named Ronald Unz, it is backed, according to repeated opinion polls, by at least half of the state's Hispanic voters.

They include Virginia Martinez, a former bilingual education teacher here in Santa Ana, a town an hour south of Los Angeles with the largest concentration of Hispanic immigrants and their offspring in the country, according to national census data.

Here, where the issues of immigrant absorption and bilingual education are particularly pronounced, Martinez tests for English competency at Taft Elementary School, which has foregone bilingual education for the past 13 years, favoring English immersion, the aim of Proposition 227.

"I kept seeing kids doing poorly in the upper grades after they had gone through bilingual education," she said. "There was no transition to English. I felt that bilingual education was holding them back."

In the school, Hispanic and Asian children learn in English from the first day, with the occasional translation help of teacher aides. High scores reflect clear success, although Taft serves a more middle-class and ethnically mixed population than many schools with bilingual programs.

At the same time, Pio Pico Elementary School, just a few miles away, is a reminder of what bilingual education was supposed to be. Built on a lot once overrun by gangs, now an oasis of learning and community involvement, Pio Pico serves a uniform population of low-income Mexican and Central American immigrants who believe deeply in bilingual education.

"With bilingual education, I am involved with my daughter's schooling," said Martha Leon, a housekeeper whose daughter, Lizeth, is in fourth grade. "My daughter is learning English, but because of the Spanish, I feel the school is mine, part of me."

This issue is not confined to California. Backed by a broad range of politicians, including then- Gov. Ronald Reagan, bilingual education emerged from the civil rights era and was supported by its own Supreme Court decision, the 1974 Lau vs. Nichols ruling.

Aside from California, 10 states mandate bilingual education, and most others permit it. Since 1968, when Congress first passed the Bilingual Education Act, the federal government has helped fund it. And while not one of those programs yet faces a sweeping initiative like that in California, all are under debate if not outright attack and curtailment.

In Chicago and Denver, school boards have recently limited bilingual classes to three years; in Arizona, the legislature has voted to limit funding for them to four years. In Albuquerque, parents are suing the school system, alleging that bilingual classes segregate their children, a charge that had been leveled at New York state by parents in Brooklyn, N.Y., three years ago. This followed a Board of Education report asserting that bilingual programs had failed to teach children as effectively as those in English-only classes.

Supporters of bilingual education contend that the programs have never been adequately supported or implemented and are thus unfairly blamed for the shortcomings of Hispanic education in this country. Most Hispanic students do not study in bilingual classes because there are not enough classes to accommodate their rapidly growing numbers. Moreover, most bilingual classes take place in underfunded school districts, adding to the difficulty of assessing their effectiveness.

What is clear is that demographics will only add urgency to the debate. In California alone, 100,000 Mexicans arrive legally each year, an unprecedented immigration from a single country that is slowing their assimilation. Nationally, by 2008, Hispanic-Americans will outnumber blacks and form the nation's single largest minority group.