Republican presidential candidate Robert J. Dole, warning that "ethnic separatism" is a threat to American unity, yesterday called for making English the official language of the country.

In a speech to the national convention of the American Legion in Indianapolis, the Kansas senator also attacked proposed national standards for teaching American history that he said would destroy youngsters' belief that "this is the greatest country on the face of the Earth." And he renewed his previous pledges to clean up movie and TV screens, end affirmative action and pass a constitutional amendment against desecration of the American flag.

In introducing the newest plank of his conservative social-issue platform, Dole declared that "with all the divisive forces tearing at our country, we need the glue of language to help hold us together. If we want to ensure that all our children have the same opportunities in life, alternative language education should stop and English should be acknowledged once and for all as the official language of the United States."

Dole is not one of the 17 co-sponsors of legislation by Sen. Richard C. Shelby (R-Ala.) to make English the official language, and campaign press secretary Nelson Warfield said last night Dole has not made up his mind about the specifics of the bill he might support. In his speech, Dole focused instead on the need for teaching English to immigrant youngsters.

Most of the pending bills declaring English the official language require that all government business be conducted solely in English and all public documents be in English, with exceptions for public health and safety services and some judicial proceedings. Some of the bills go further and ban bilingual education and bilingual ballots.

Sen. Richard G. Lugar (R-Ind.), a rival for the nomination who is a co-sponsor of the Shelby bill, said he believed, "as a practical matter, every immigrant needs to master English to be a full participating citizen and to have full economic opportunity." Lugar said, "I appreciate Senator Dole's affirming it -- in my home town. I say welcome aboard."

In 1987, President Clinton signed a bill as governor making English the official language of Arkansas, but Democrats in Congress generally have opposed federal legislation in this area.

White House spokeswoman Ginny Terzano said Dole's proposal "is not realistic because so many young students don't speak English, and in order to communicate with their teachers and reach full competency in their courses they have to be taught in Spanish" and other languages.

Yesterday's speech was the first of a pair that Dole campaign strategists said were designed to restate the broad themes of his candidacy before the Senate majority leader plunges back into the nitty-gritty legislative battles on Capitol Hill. Today, in Chicago, he is expected to spell out his economic policy differences with the Clinton administration and outline his ideas for a simplified tax system that would reduce rates and transform or even eliminate the Internal Revenue Service.

The audience of 6,500 fellow veterans provided a warm welcome for Dole, whose status as the early favorite for the 1996 nomination was jarred by a series of psychological and public relations setbacks during the August congressional break. He was tied by Sen. Phil Gramm (R-Tex.) in a straw vote in Iowa, expected to be one of Dole's strongest states, and was embarrassed by a controversy over a campaign contribution from a group of gay Republicans, which he decided to return.

"He's shown some slippage," said Dan Schnur, a spokesman for another rival, California Gov. Pete Wilson (R), "but he's still a couple laps ahead of the field."

Dole was criticized, even by some supporters, for appearing too casual and unfocused in remarks to the Iowa convention and to a meeting a week earlier in Dallas of several thousand supporters of 1992 independent candidate Ross Perot. For the Indianapolis and Chicago speeches, he promised to return to the formal texts and professionally crafted rhetoric he used on his well-received announcement tour last spring. Yesterday, he kept his ad-libbing to a minimum.

As he has done repeatedly in this, his third bid for the presidency, Dole reached out very publicly yesterday to the conservatives in his party who in the past have criticized him for being too much a non-ideological deal-maker.

His endorsement of legislation to make English the official language drew a scornful comment from one conservative rival, commentator Patrick J. Buchanan. "Senator Dole is really violating the copyright laws," Buchanan said in a telephone interview from Florida. "I came out for this in 1992, and I said then that all federal funding for bilingual education should be ended."

Wilson also entered a paternity claim to the English-as-official-language idea, citing his support of a 1986 California initiative to create such a status for English in that state. However, Jim Boulet Jr., head of the advocacy group English First, said, "Wilson has failed to enforce the law. It's nothing but grandstanding." A Wilson spokesman said the governor's efforts had been "hamstrung" by the Democratic legislature.

The Dole campaign staff said the senator had supported a nonbinding resolution to have English declared the official language in 1982 and cited other examples of votes germane to the position he advocated yesterday. An aide said yesterday's speech was intended as a "broad discussion of the issue."

Dole said that "schools should provide the language classes our immigrants and their families need, as long as their purpose is the teaching of English. . . . But we must stop the practice of multilingual education as a means of instilling ethnic pride or as a therapy for low self-esteem or out of elitist guilt over a culture built on the traditions of the West."

In criticizing the history standards, Dole said they overemphasized negative aspects of U.S. history such as "the scourge of McCarthyism and the rise of the Ku Klux Klan." He blamed the standards on the same "liberal academic elites" that he said created the controversial Smithsonian Institution display on the anniversary of Hiroshima that suggested "dropping the {atomic} bomb was an act of American violence against Japanese culture."

"Today," he told the Legionnaires, "even Japan has finally apologized for its atrocities and aggression, so maybe it's time the Embarrassed-About-America Crowd gets the message too: We're proud of our country. And we won't put up with our tax dollars being used to drag it down or sow doubt about the nobility of America in the minds of our children." CAPTION: Before American Legion in Indianapolis, Sen. Dole criticized history teaching standards. CAPTION: Dole speaks to fellow veteran at American Legion convention in Indianapolis.